Contemporary Art Porcelain

Venco Reassembled

2011-04-17T05:49:00.004-04:00

Yesterday I got the Venco totally reassembled and tried to pug some stoneware clay through it. The first thing I encountered was that my little taping of the screens was way too aggressive and I had to remove them and take all the tape off and then just retape the top 2.5 inches. What was happening is that clay was totally filling the slot which allows a vacuum to reach the clay. It works much better now.

But, and I accept suggestions here, it will not pull a vacuum. The vacuum pump, which is one of the old Clisbys, is working fine. If I put my finger over the hole it goes straight to 28+ inches of Hg. But with the NEW gasket in place, and just about every old and new gasket I could find or make from the stuff I have around, except the old one which I stupidly threw away, it will not go above 5 inches Hg.

Since the middle gaskets were of electrical tape, and since clay got real dry around the gaskets if the mill was not used for some time, I made new ones out of Buna-N rubber, the same rubber that separates the top and bottom pieces on my Shimpo stainless steel mill. I also made the vacuum chamber gasket out of this Buna-N rubber but it really leaks. Badly.

I have a really nice lap wheel and so took one of the metallic diamond pads and attached it to a flat piece of metal, and sanded the top of the vacuum chamber until it was flat, which took some time. Did not help a lot.

The top piece of plexiglas is the piece that came with the pugmill and it is not totally flat and many years old -- close to 25 probably. I tried some other pieces of thin plexi and they did not work either.

So. What to do? The first thing is that I will block off the vacuum chamber leading into the pugmill and make sure it's the gasket at the top of the chamber that is the problem. I think it is but it could be the Buna-N rubber which runs down the seam of the top and bottom pieces of the chamber, or the Buna-N pieces that protect the plates where the screens are extracted. I don't think it's this because the Shimpo works fine with the Buna-N.

I do not tend to have great mechanical ability. A problem like this one stumps me for some time. The mill has lots of clay in it so it's not open at the end, as a Venco can tend to be. Interesting problem.

Suggestions appreciated.

Cleaned Out Venco Pugmill

2011-04-04T21:11:00.002-04:00

I've not cleaned out my Venco Pugmill for several years and it just seemed like the time to do it because I was not getting a good vacuum and there looked to be lots of corrosion. I had decided to install Buna N rubber gaskets all the way around to try to get the vacuum tighter, and to try to have less air seeping through the joints. When I don't use the pugmill for several months there is a noticeable dryness at the horizontal seam that runs the length of the pugmill. Venco recommends electrical tape for the joints, but over time, air gets through and it causes problems with stuff spalling off the sides into the clay, and the hardness I mentioned.

One test that I used was to take a pug and twist it, and in so doing there were air bubbles and delamination. So I decided to tape the screen aggressively so that the total amount of volume that needed to be deaired was less than before, and was nearer the vacuum chamber. As luck would have it, Rick McKinney of MKM Tools stopped by and he noticed that the screens were polished where the most clay went through and suggested that I tape with this in mind and so I did. Not sure how this will work, and for sure the mill will be slower, but I hope it helps. The mill is too fast anyway -- hard to keep up with for one person.

New Drying Molds

2011-03-14T16:16:00.003-04:00

I mix my own clay, both stoneware and porcelain. At this point in my career I want to be sure that it is done like I want it done, and want to be able to mix small enough batches so that the formula can be flexible when conditions change. The old drying bats were just totally worn out. So we made some new ones last week. Here is a view of the process with the bus pan balanced in the wet plaster, and all the sides clamped up. We actually needed that wrench to balance the load.

A very quick little mixing formula is 2.75 pounds of plaster added to 2 pounds of water makes 81 cubic inches.

Here is the finished bat. 50 pounds of plaster and 36.6 pounds of water.

I always line the bat with a double layer of cotton sheet and then pour in the slip. After a couple of days the sheet can be removed with the clay and the bat can be allowed to dry. With these new molds that might not be necessary, but I will probably still do it.

Owen and Nadia's Pieces -- Part 2

2011-03-13T18:46:00.005-04:00

Owen and Nadia's Pieces.

This last week I got to fire Owen and Nadia's pieces. Owen's piece is a dog with an invisible fire hydrant, and Nadia's is a Macaroni Penguin, something which I had never heard of, but sure enough, if you Google Image them, they are there in all their glory. Before Nadia glazed her piece the head came off and we glued it back on. In thinking of what might happen in the firing, I decided to make an executive decision and fire the head separately. It was the right decision. I made a little conical clay support and glued the head to it. Some of the macaroni also came off and I made a little clay pedestal and fired them so that they could have shiny glaze like the pieces do. Here they are unfired just before stacking in the kiln.

And here they are fired, but not assembled.

Dupuytren's -- The Surgery

2011-03-13T16:18:00.005-04:00

Friday was the day that I went to see Dr Eaton at The Hand Center in Jupiter to get my hand fixed. It turns out that I had something that had to be removed and the surgery that I thought I was going to have was not going to work; there was a skinny tunnel into the hand about the diameter of the metal part of a wooden needle tool and about an inch long and covered with hardened fascia, and it was going to have to be removed. I had driven 300 miles and so Dr Eaton just numbed up the hand and we waited for about an hour for all the components of the medicine to work. There was the anesthetic, of course, and then there was epinephrine which is a vaso-constrictor which helps with bleeding, about 3 cups of coffee worth, taken in about 1 minute. Soon I was just zooming.

Dr Eaton's mom is a potter so he has a real appreciation for potters. All through his childhood there was a wheel and kiln at his house, and his mom made pots.

The reason I went to see him is that my friend Alan Stowell, guitarist, violinist, mandolinist extrordinaire had a Dupuytren's repaired several years ago using needles and all traces of it are totally gone. So I already knew that Dr Eaton was an incredible craftsman, and I felt totally comfortable with him and the staff.

I sat in a chair and watched the whole thing and it was fun in a weird sort of way. Anne and her sister Trish were walking on Jupiter Beach but they came over to the office when they found out that this was going to be more involved than we had originally thought. When they got to the office they said that it sounded like we were having a party back in the operating room -- lots of laughing and carrying on. Friday afternoon, you know.

Here is a photo where Dr Eaton is holding the tunnel just before removal. Don't look if this sort of thing will not be interesting to you.

I can't make pots for a couple of weeks but have talks to prepare for NCECA related events so this is a good time -- and it's over!

Oilspots

2011-02-26T18:02:00.003-05:00

Jim asked about the oilspot bowls and so here is one from today's firing. It was in the bottom of the kiln, and it only went to cone 8, so it's kind of muddy and not as nice as the ones from the last firing, which were hotter. I have plans to open up the bagwall in my kiln so that more heat gets to the bottom, but this firing was all about two very large copper red covered jars, and the kiln was fired to maximize them, so these bowls were an afterthought as it were.

The bowl below was in the previous firing and it's much nicer, at least to me. These two bowls were identical before putting them in the large kiln, in fact the bowl below was the one I deemed to be the worst of the batch. There were 4 bowls in this firing and I will probably fire them again, or at least pick the worst one and fire it.
The large jars are nice, but I want to fire them again because I think I can make them nicer.

Firing Today in Car Kiln

2011-02-24T19:40:00.002-05:00

After struggling with the flu/cold for the last week, I was finally able to fire the large gas kiln today. It was actually the first day that I have had enough energy to do this firing, although the pots have been ready for a week. The photo below is of two large covered jars, which if all goes well, will be a beautiful copper red. So much can go wrong with these and I am a bit apprehensive, though it appears that things went well.

Above this saggar, are several shelves of dinner plates and bowls, and a couple of horse sculptures by my friend Bill Schaaf. There are also some oilspot bowls hiding here and there.

I must say that when I tried to push the car in, things were a little cramped and minor surgery had to be performed to get the car to settle correctly, well not quite correctly, but close. There was about a quarter inch at the bottom where the car did not touch and I did not notice it until the kiln was already hot.

Hans Coper

2011-02-19T14:21:00.003-05:00

A new post by Tony Clennell got me thinking about how much I love the work of Hans Coper, and how I have been influenced by him over the years. It is without question that Hans Coper is my favorite potter of all time. Perhaps because when I was a young guy of 24 years old, just beginning to make pots, I found a book with lots of his work in it and was hooked.

I call these pieces "Hourglass Vases" and the first one sits on Anne's dresser so I get to see it every day. It's a little under 12 inches tall, thrown in one piece. It has a titanium crystalline glaze and was fired in reduction to cone 10, 11, 12 -- somewhere around there. Both vases were multi fired with lots of grinding, spraying and cussing in between firings. I know how to place a darn or gosh for maximum effect.

This green one is from the same period, and about the same size. Both were made between 1994 and 1998, and both these images are from scans I just received back from ScanCafe. I must say that I like the quality of the work they do. I will make a post about my experience with them if anyone is interested.

In this case, the glaze was applied evenly by dipping, but the fire drew the pattern on the piece. Sort of like wood or soda firing, except with much less success. These glazes were so hard to do that I just stopped making them.

To me these pieces are about opening and closing and then opening again. If we really want to, we have the right to live our lives with an open heart. And that's what these are about for me. They are a technical challenge which makes them fun to make, and they are an aesthetic challenge because there are a lot of really bad forms lurking in there, and the strategy must be precise to get a good one.

Lennie

2011-02-13T18:40:00.005-05:00

John Bauman just had a post about inspiration and it got me thinking about things I do to keep myself inspired to keep making stuff.

One of the things that I have done for the last 30 years is a collaborative series of pots with my friend Lennie Kesl. In about 1980 Lennie and I were both teaching at Santa Fe Community College in Gainesville, and I asked him if he would like to decorate some pieces if I made them. He was thrilled and we thus started a body of work that has persisted all this time. We started out with stoneware and slips, progressed to stoneware with underglazes, white earthenware with underglazes, and finally to red earthenware with glazes, underglazes, slips, crystals and whatever else Lennie can put on there. This first one I call the Alien because it seems very strange to me, like it's from some other planet. The glazes and underglazes are built up, sometimes a half inch thick.

This one here is a bit crazier. It's about the size of a dinner plate. Both of these were done in 2004.

Finally this last one is kind of a takeoff on Pre Colombian ceramics. We really have fun with these and this one was one of the most fun. You can not see it here, but there is a face which is facing straight down, and one of the tripod legs comes right out of that face's third eye, as if a horn on a devil. Lennie is quite serious when he does these, and while the humor is there for all to see, Lennie is very serious about it all.

Lennie turns 84 in June. We are going to make some more things real soon.

It's Time

2011-02-09T19:38:00.003-05:00

I've started to dry out these 7 glaze buckets because the glazes have not been used for 12 years and it's time. These are all titanium crystal glazes that I fired in reduction and you can see some examples of them at gallery.me.com/johnetilton#100130

It's hard to just let this go. Those were nice glazes but they were just so difficult to use, and the success rate was so small, that it was just not reasonable to continue with it.

The Fallonator -- Part 2

2011-02-05T21:59:00.003-05:00

My friend Phil, who owns one of the only Fallonators in captivity, has posted some pictures on his blog and here is a link.

http://puttgarden.com/crystal/tech/Vendors/fallon/fallon.html

John

The Fallonator

2011-02-05T19:44:00.002-05:00

It's a very long story, and one which for now will be without pictures, but my friend Terry Fallon has been developing an automatic reduction system for an electric kiln and it works very nicely. He got this idea a few years ago and I was able to be one of the 5 people that he bounced ideas off of which was wonderful for me because I know nothing about engineering -- though that was my first major in college. But I had fired reduction kilns and was very interested and so I was allowed to tag along.

Anyway, here is the scoop. Terry is beginning to build some systems that are add ons to existing electric kilns. The reduction is accomplished from a small propane bottle like you would hook up to a hand torch. There is an oxygen probe made from an oxygen sensor from a car, and you can program the amount of reduction that you want and it will do it. Terry has a special motherboard that allows you to say, in each segment of the firing, whether you want reduction or not. The kiln can be fitted so that it will send both temperature and reduction information wirelessly to a computer, and you can see the graphs in real time on the same chart. It's pretty neat. Very neat.

Fuzzy Green 2

2011-02-05T19:20:00.005-05:00

Here is the Fuzzy Green pot that came out this afternoon. It's a bit different from the first one but quite similar. This one had 4 soaks instead of 2, but the rest was mostly the same. Same batch of glaze, same top temperature, same thickness of application. I found the glaze a little difficult to brush and so I am going to ball mill it some more tomorrow afternoon. I say ball mill, but I have a 30 year old Lortone Rock Tumbler and it is not really a ball mill at all, but it does do a good job for me.

This second photo is a top view of the pot above. You can see the first Fuzzy Green pot in the background. Both of these pots are resisting my efforts to separate them from their pedestals with a torch. This fuzzy glaze is quite hard and it makes a strong bond between the pot and the pedestal.

You can see the cone next to the pot in the bottom photo. I write the name of the firing on the cone -- BB 6-83 -- so that I can reference it in the future. That's the 83rd firing on the 6th set of elements in the kiln called Baby Bear. Mama Bear and Papa Bear are on either side keeping guard.

The Fuzzies

2011-02-04T21:33:00.003-05:00

Here is the Fuzzy Yellow pot that got fired the other day. It is pretty nice and the glaze eventually behaved. I had to scrape the glaze off the top of the pot 3 times before I finally got it to stick. The pot was glazed by brushing.

Here is the Fuzzy Green glaze that I mentioned. This one just came out this afternoon and it is still on its pedestal, glazed to its catcher. Another hard glaze to make work. What really attracts me to these fuzzy glazes is how nice they feel in your hand. They are really smooth and the glaze also has some internal sparkling and you can see little specks when the light is just right. It's obvious that this is a matte glaze, but this is the most matte of all the glazes I use. Nothing shiny about it, except for that little sparkle.

I fire these mostly one at a time, and change things between firings. I have another pot in tonight, a Fuzzy Green but with a very different firing profile, so it should be quite different. Though I do like this one. And another one for tomorrow night.

Another thing I am trying to do is figure out just which parts of the crystal grow at which temperatures, so I can design effects because different colors happen at different temperatures. So this pot had just two holds beyond the top temperature and yet the crystals are very complex. I was expecting something much more simple but am not complaining.

Glazed Pots

2011-01-29T05:24:00.003-05:00

I spent a better part of the day yesterday airbrushing these bowls and plates. What you see here is the pots glazed, but before airbrushing. There are 2 coats of the tan glaze, 3 coats of the blue glaze, and a brushed coat of a glaze I call Gatorskin, which is a slip based ash like glaze. I also airbrush Gatorskin so that the effect of it is very subtle and feathered, rather than hard edged if it were brushed at the end. This first photo is looking from the front to the back of the shop, north to south.

The photo below looks from west to east and you can see the dinner plates ready to be airbrushed. Perhaps you also notice a water purification system on the wall in back. We have very bad water here in the woods, and this system is an attempt to get good water. It works very well. The water has less that 10 ppm dissolved solids, and tastes wonderful. I also use it for glazes, and mixing clay too. I have started mixing all my own clay.

The old refrigerator gave up the ghost a couple of months ago, and I have not wanted to buy a brand new one, and have not checked Craigslist faithfully for oldies as I will have to have help loading it into my truck, and I am just so busy with the commitments of these pots. But soon a "new" refrigerator will appear. Perhaps the one at our house which is now just 20 years old.

ScanCafe

2011-01-28T07:11:00.004-05:00

I have slides that are over 40 years old and it is time to digitize them, especially since NCECA is in Tampa/St Petersburg this year and I'm involved and will need to make a couple of presentations. So I sent 30 slides off to ScanCafe to see what they would do with them. I am happy with what they did and now I am going through all the slides I have from 1968 to digital, which is about 2002, I think. There are thousands.

This is one of a close up of one of my second year graduate school works. It is a slab built round pot, and you see the top. It was lightly rakued, a process I called "Smoked Raku." Its diameter is 16 inches. I will post some of the other ones from that period, including the firecracker pots and the flocked pots, as soon as the scans come back.

ScanCafe is inexpensive if you get lots of slides scanned, but the shipping is expensive for just a few. That said, it was worth it to just see what their quality would be and not commit hundreds of slides only to be disappointed. This image is clear, faded for sure, but I think it can be helped with Photoshop. It did not have much color anyway.

Fuzzy Yellow

2011-01-27T19:24:00.003-05:00

I have been trying to get this glaze to work for a couple of years and it has been an incredibly difficult one. I call it Fuzzy Yellow; there is also a Fuzzy Green, which is difficult too. This one came out yesterday and it is what I'm looking for. It's extremely matte and very smooth to the touch, really nice to hold in your hand.

I have another pot which will fire tomorrow night with the same glaze and the same firing cycle and hopefully will be as nice. These glazes are finicky and even though I do the same thing and fire the same way, I do not expect the results to be the same. But hopefully doing the same thing will make for a successful piece.

Kiln Disaster

2011-01-22T19:47:00.003-05:00

Here are a couple of photos of the kiln disaster. It was a copper red firing and the bottom octagonal shelf just melted with all the weight on it. This first photo is before anything was unstacked, and you can see that the bottom shelf appears to be missing. It's in there somewhere.

This next one is of a piece of that bottom shelf. Hard to believe it was rated for cone 10, but I have fired those shelves to cone 10 many times, just not with so much weight on them.

This final photo is also of that bottom shelf, the largest piece of all the ones I chipped out. It's stuck to the kiln post, and there is major glaze running.

The shelves above the copper reds were fairly OK. The pots all need to be refired, but they did not collapse as they might have. There is lots of pinholing on the glazes, but I have seen worse come out beautiful in a second firing.

I fired the kiln yesterday to red heat just to make sure the patching was dry -- it has been a month -- and the new target brick, a 12 x 12 x 1 inch slab of alumina, would be able to withstand a burner about 10 inches away and not crack.

The alumina slab came from a friend and it weighs 22 pounds. When I picked up the package I was really surprised by the weight. I was expecting maybe 8 pounds. I've not unstacked it yet so don't know whether the slab is OK.

Graduate School -- USF -- 1971

2011-01-20T06:16:00.004-05:00

I went to graduate school in Ceramics at the University of South Florida in Tampa and since NCECA is in Tampa/St Pete this year, I just had some slides scanned. Both of these slides are of my work at the end of the first year, which would be the early summer of 1971. We had to display our first year's works to see whether we would be accepted to continue and this was my setup. Casual. The whole place was casual. But effective as all the professors came out to see it, and I was allowed to continue.

USF was a very new college at that time and the view you see here is long gone, with buildings everywhere. Almost all of the professors were under 35 years old, so it was a young place and very stimulating. New, progressive, confrontational. We had people like James Rosenquist and Robert Rauschenberg making work down the hall from us in the GraphicStudio, and the place was teeming with energy.

I'm not sure how these pieces relate to my current work; I had only been interested in Ceramics for 3 years at the time, and so these were some of my early pieces. This was also before I decided to become a potter so I was not trying to make pots. Pots were not looked upon as a valid direction for a graduate student at USF. I had shelves in my studio and kept black plastic over them and made pots on the side all my way through grad school. Fired them on the weekends. So I really had two bodies of work going at the time and the professors knew about the pots, did not seem to mind much, but they never saw them.

Night Firing

2011-01-16T21:43:00.002-05:00

This is a picture of a firing that we did just before our Holiday Show. It's just getting dark and the kiln is very hot at this point. I wish I could say that every thing turned out well, but it did not. One of the bottom shelves warped badly and the whole stack fell. We had to chip a lot of stuff out of the kiln and then repair the brick with a castable refractory, and, as of now, I have not fired it again while waiting for the refractory to dry completely, but it's ready to go now and I hope to fire it soon.

Dinner Plates

2011-01-14T06:44:00.003-05:00

Well it's not all porcelain around here these days. At our Holiday Show people kept asking for dinner plates and here is the first half of them. I made 25 altogether, including ones for our home that Anne asked for. Never hurts to order when everyone else is ordering.

While I love to make porcelain, I also love to make pots that people can use every day. A mug that someone might cherish gives me great satisfaction, and I love to see lots of pots all lined up neatly, ready for the next step, whatever that is. There were also orders for bowls and I got all of them in except for 4 hiding on the table in the photo below. They are lined up in a square, but even 4 makes me happy. It's 25F here in North Florida this morning and the large electric in the photo, Papa Bear, is firing to go off around noon. We are going for heat today.

Here is what the plates will look like when they are fired, well, except that they will be plates instead of pie plates. I use two different matte glazes and then spray an ash like glaze in the interstices of the glazing process. Each piece is glazed with many layers which require handling the pots several times before stacking them into the large gas kiln, where they are reduction fired to cone 10, around 2350F.

I do have to say that these pie plates bake incredible pies. Anne makes an apple pie every Thanksgiving and a cherry pie every Christmas and the pies are always wonderful and crusts are always perfect. They are a bit larger than the traditional pie, but, what the heck, it just means more pie. Yum.

Owen and Nadia

2011-01-06T20:08:00.003-05:00

The other days some folks came out to choose a present for a friend and their two kids each got a little sample of clay to play with. I was just amazed by the little pieces that they fashioned. Owen made this little dog and Nadia made the standing figure. I find both of the figures humorous and gesturally wonderful.

I'm not sure whether Owen meant for the dog to have his leg up, or if the piece just dried that way, but, as you can see, he is definitely a male.

The pieces got loaded into the bisque kiln this afternoon and they will be fired tonight. I found myself being much more careful with these pieces than with my own as I do want them to come out successfully.

Happy New Year 2011

2011-01-05T21:24:00.004-05:00

Well here is me making the first pot of 2011, a small bowl in a set of 8 which will be used for pasta. I usually don't make dinner plates but several people wanted from 2 to 6 plates and the total I am making is 25. I don't think I've ever made 25 dinner plates at one time so this is a nice project. There are also several sandwich plates, bowls, and even a spoon rest to make.

The shop is quite disorganized at the moment and I hope to get some real work done on that tomorrow. There is 33 years of accumulated stuff laying around and it's time to begin to cull the stuff I will never use again. There are thousands of test tiles that could be digitized and turned into a wall or thrown away. Boxes and boxes.

Something weird is happening in my hand and I think it might be a Dupuytren's Contracture. It is like someone stuck a needle into my hand going up the little finger and there is a hard something inside the hand. It is beginning to pull the finger towards the hand.

Please Don't Burn the Koran

2010-09-06T11:55:00.004-04:00

I know it has been over one year since I have posted anything and I have had some stuff to say but have felt too lazy to say it, but something is happening in Gainesville, FL, my home town, that is receiving international attention, and it is not the good kind.

There is a small church of less than 30 people and the pastor is planning to burn copies of the Koran next Saturday, September 11. People all over the world are protesting. There have been protests in Indonesia and Afganistan, and the main problem is, that these people probably think all Americans feel as this man does. America is burning the Koran, not some quacky pastor in some small church.

This is such an act of disrespect to the billions of people who read and love the Koran, that it is hard for me to find the words to express my outrage. But this affects us all, really everyone in the whole world. It's an act of disrespect to everyone in the whole world. It is heartbreaking.

I have found that almost all of us in the pottery community are very spiritual by nature, and whether or not we are religious, we respect others and their right to pursue their spirituality as they choose. And we work with our personal energies as a way of life. An understatement.

I ask you to go to this website and sign the petition. It takes less than a minute and your comments will be delivered to this man on September 10.

www.thepetitionsite.com/1/PleaseDontBurnTheKoran/

Thank you everyone and I promise to begin to post again.

John

Element Design --- The End

2009-06-18T21:15:00.003-04:00

I just thought I would try to end this thread by not going mathematical, but by speaking about the parameters that you need to be able to keep in mind when you are designing elements for a kiln. Anyone who is interested in how we did Papa Bear just let me know and I will do a separate post on that.

At any rate this will just be a review and crystallization of what we have done so far.

The most important variable is what is called watt loading, or the amount of watts per square inch that the elements have to generate to fire the kiln. Larger diameter wire allows for lower watt loading figures, but you have to be able to fit the wire into the kiln, and larger diameter wire also has less resistance per linear foot -- it's easier for the electrons to pass through a larger wire. So as you make the diameter of the wire larger, you need more of it to achieve the resistance that you need, and it may be so much wire that it won't be able to fit. We found that 12 gauge wire worked well for us, and that Kanthal A1 was the alloy that is the most economical and useful at the same time. Kanthal also makes an APM element but the raw wire cost is almost 5 times as much. It is special wire and I feel like it is not worth the extra cost as long as you have low watt loading. I think the watt loading for Papa Bear is around 12 watts per square inch. If we had decided to use 15 or 16 gauge wire, the APMs might have been a good choice, as they can go to a higher temperature.

We also have to take into consideration the diameter of the element. The diameter should be, according to Kanthal, about 5 to 6 times the diameter of the wire. Once we wind the element so that all the wire is touching we need to be able to pull the element to just over twice its wound length. The distance from the top of one wire to the top of the next wire is called the pitch and we want it to be just over 2 times the diameter of the wire. So we should be able to put a piece of element wire of the same size in between the stretched coils and move it back and forth a little.

We need to know how large our kiln is and how many kilowatts it will take to fire it. The Robert Fournier book has this information.

And we must keep in mind what happens when elements and banks of elements are wired in series and parallel.

Here is Galen Olmstead changing the element holders so that Papa Bear can accept the larger elements. We had to grind the element holders on the lap wheel so that we will be able to easily install the elements. Galen is beginning graduate school at UF this fall and he makes some wonderful sculptural objects.

John

Element Design --- Answers to Questions -- Part 5

2009-06-11T06:50:00.002-04:00

I was thinking that this thread has gotten out of hand by being so technical --- and no pictures --- which is why I shortened it but here are the answers to Dan and Alex's questions.

When I got Papa Bear I had discussed my needs with L&L and they sent this large 29 inch diameter kiln with 18 gauge elements, and the elements had almost no stretch to them. The kiln fired fine for a few firings and then it would not get to temperature quickly enough. I will mention that zinc crystalline glazes are quite caustic to elements and kilns so this was a new problem for them and that they have been really open to learning and overcoming the problems that we have. But anyway the kiln was underpowered and I just started using it for earthenware and bisque. It now will not even do that so something had to be done. The kiln was rated for less than 40 amps and that was not enough to make it useful.

I did not want to learn about element design because it hurts to try to keep all that stuff in memory at one time. But I have this kiln that is totally useless, and I wanted to bring it up to useful.

My smallest kiln, Baby Bear, has 137 firings on one set of elements so I know that there is a way to design elements so that they last a long time, but I don't know how to do it. I'll get a picture today of the elements of Baby Bear. There are twice as many element holders in Baby Bear as a normal kiln.

These new elements for Papa Bear, 12 gauge Kanthal A1 wrapped around a 3/8 inch mandrel and 8 ohms cost 72.00 each and the kiln needs 8 of them so a good part of this is wanting elements that last a long time. But it is also important for the kiln to be nimble -- able to reach temperatures quickly (both up and down) -- say at least 200F/hr at the end. Eventually this figure will not be able to be reached and we will have to replace the elements, but we want to be able to use them for as long as possible as 576.00 is 576.00.

By the way, if you have a newer Bartlett controller and you press 5 while the kiln is firing, it will tell you how fast you are going. Mini tidbit but impressive for onlookers.

It is true that my work requires more precision than most, but the principles apply to anyone who fires to cone 9 or 10 --- your elements will wear out at some point. Ray Gonzalez, who is the tech person at UF, says that kilns fired to cone 6 and below rarely need element changes.

One thing that is a good question is whether the kiln manufacturers should design their kilns for us. I say no, it is not their responsibility. They have to compete with one another and they have to make the best product that they can within those parameters, but they make "hobby kilns" and we have to adapt them to our purposes.

It's true that the L&Ls are made like a tank. If you stacked boxes of clay on top of an L&L stand, you would be able to go until the stack fell over. That stand could probably hold 500 pounds or more. Every other kiln that I have had has had a less robust stand, and I have had a few. Not that the stand does not still work, but I did get a feeling of confidence the first time I held an L&L stand.

Tonight I will go over the math stuff again but I am the cook today for the community and it basically takes all day to shop and cook. I cook every other Thursday. Yesterday was Anne's birthday and she requested black bean soup with amarillos and tostones and salad so that is what it is. Maybe a photo of the whole meal tonight if I can remember.

John

Element Design --- Our Final Idea --- Part 4

2009-06-10T21:59:00.003-04:00

Well those elements are ordered and we now just have to wait for them to come. I sent the controller box down to Terry so he could install the Solid State Relays. These relays cycle on and off every 200 milliseconds so the elements do not get that much hotter than the kiln.

Here is what we decided to do. There are 8 elements in all in the kiln, three in each side section and two in the floor. We divided up the kiln into 4 sections of 2 elements each. This is quite different from how the kiln was originally wired, which was a 3, 3, 2 configuration.

Each of these pairs of elements will be wired in series within the pair, and all 4 pairs will be wired in parallel to each other. The elements will be 8 ohms each so each section will be have 16 ohms of resistance and 15 amps of current, and all 4 sections will generate 60 amps.

The wire is going to be 12 gauge Kanthal A1 wound around a 3/8 inch mandrel. This gives us a very good length to the element -- when it is stretched the pitch is just about perfect. And the watt loading figure is very low so these guys should last a long time.

Let me know if I need to be more specific about any of this -- how we did it, why we did particular things.......

John

Little Lemma Dilemma

2009-06-10T21:51:00.002-04:00

Thank you Lee for the nice pun.

In my "Little Lemma" post near the bottom I mention about how my thinking had changed and now I have to admit, that was from right to wrong. I got out the Fournier book and saw that to get the distance it takes for a wire to wrap around a mandrel, you add 2 radiuses to the diameter of the mandrel, not two diameters, as I had. Sorry for this.

After thinking about it so many ways, and consulting my friend Terry Fallon, we have finally decided on the elements for the kiln.

John

Little Lemma

2009-06-05T00:33:00.003-04:00

In one of my past lives, I worked towards a PhD in Mathematics, and could not resist throwing in a math term. Never did finish it but I have a Master's Thesis around here that is unintelligible to me now. Did I actually understand that?

A lemma is a small theorem which is used to prove a larger theorem.

Suppose that we are going to wrap an 11 gauge wire around a 3/8 inch mandrel. How much wire do we need to go around once?

OK. What do we know? We know that 3/8 inch is .375 inches and that the wire diameter is .091 inches. We also know that the circumference of a circle C = πd where d is the diameter of the circle and π is 3.14.

So what is this diameter? It has to take into account the diameter of the wire. It certainly looks to me like that diameter is .375 + .091 + .091= .557 and that the circumference is .557π = 1.75 inches. That is, it takes 1.75 inches of 11 gauge wire to wrap around a 3/8 inch rod one time.

Here is my thinking. It has changed since I started writing this so I might be wrong. 1.75 inches is the circumference of the rod plus two wire diameters so it is the outside circumference of the wire wrapped around the rod.

If we measure around the outside of the wire we get our answer. And anything less is not going to meet up.

John

Element Design --- Wire Size and Pitch --- Part 3

2009-06-04T19:47:00.005-04:00

This has been a very interesting time as I am trying to understand what makes a great element and, of course, get great elements in my kilns. The whole thing has been quite time consuming, but I feel like if I understand how to do this, I can maximize the life of my elements and the usability of my kilns.

Here are my thoughts how to design elements for Papa Bear, which is a 29 inch diameter L and L kiln with 2 sections. There are 3 elements in each of the sections and 2 elements in the floor, so there are 8 elements in all. Since we want to have 60 amps, which will give us 14,400 watts, we divide the kiln into 3 different sections of 20 amps each. Each of these sections will be wired in parallel to each other.

But within each section the elements will be wired in series. So the top section will have 3 elements wired in series, the bottom section will have 3 elements wired in series, and the bottom of the kiln will have 2 elements wired in series. That makes 8 elements in all.

Let's look at the top section. We have 240 volts, we want 20 amps, so we need 12 ohms. (240/20 = 12) Since we have 3 elements in series each element needs to be 4 ohms.

Now there are a lot of ways to get an element of 4 ohms depending on the diameter and type of wire, but I have decided that I am going to use either 11 gauge or 12 gauge Kanthal A1 wire. 11 gauge is thicker (.091 inches) than 12 gauge (.081 inches) and I would rather use 11 gauge than 12 gauge because it will last longer. 11 gauge wire also has less resistance than 12 gauge wire --- .106 ohms/foot as opposed to .134 ohms/foot. It's easier for the electrons to travel through a thick wire.

However I have been told that 11 gauge wire is very difficult to work with because of the strength needed to wind the element, and also to install the wound element in the kiln. I don't have experience with this, but I do like the idea of using 11 gauge.

Let's calculate the length of the wire needed for 4 ohms. 11 gauge is 4/.106 = 37.74 feet of wire and 12 gauge is 4/.134 = 29.85 feet of wire.

Now we have to wind these wires on a mandrel and there are a couple of things we want to keep in mind, these courtesy of Kanthal. http://www.kanthal.com/C12570A7004E2D46/062CC3B124D69A8EC1256988002A3D76/D1D355F37C940491C12572B9003FD970/$file/1-A-5B-3%20UK%20resistance%20alloys.pdf?OpenElement

First of all we want the diameter of the element itself to be between 5 and 6 times the diameter of the element wire. This is so the heat can get out of the back of the element, and also so the element does not fall over when it is hot -- if the diameter is too big, the element won't be able to stand up when it is soft.

Secondly, we would like to be able to stretch that element so that we have close to 1.25 element diameters between each pair of adjacent coils. We want to be able to take a piece of wire that the element is made of, insert it in the coils, and be able to wiggle it around a little. This is so the heat from the back of the element can make it out. Kanthal defines the "pitch" of the element to be the distance between the top of one coil and the top of the next coil and they specify that the pitch should be between 2 and 3. Our pitch above was 2.25. We don't want the elements to be stretched too much so we want to keep the pitch below 3 for an ideal element.

When Papa Bear arrived the elements were of probably 17 or 18 gauge (They measure .040 inches) and the pitch was approaching zero. Just an unstretched element laying in the holders. I was only able to get a few cone 10 firings from them and now they will not even go to bisque.

Next -- the winding of the elements.

S Type Thermocouples --- for Alex

2009-05-28T22:01:00.003-04:00

If you look very carefully inside the photo of Baby Bear you will see the S Type thermocouple sticking out into the kiln. The S Type thermocouple is much smaller than the K Type thermocouple, but the thermocouple wires, which are Platinum/10% Rhodium and Platinum, are totally enclosed. The wires are protected from the atmosphere of the kiln.

The thermocouple does not in any way come into contact with the elements.

I believe they will last indefinitely if you do not break them. They are easy to break because they are small and delicate. I broke one of mine and my friend Terry Fallon fixed it.

The caustic nature of the crystalline atmosphere does not touch anything but the porcelain sheath.

I believe Omega is one company that makes them and Cleveland Electric is another. And most kiln manufacturers probably stock them too.

Element Design --- Some Basic Kiln Parameters for Potters

2009-05-28T19:57:00.002-04:00

There are a couple of features that crystalline potters should have with their kilns and I would like to look at these as a little digression from the calculations of the elements. I would say that every potter with an electric kiln should at least consider these features.

The first has to do with thermocouples. A crystalline potter needs an S Type thermocouple. There are other even more expensive thermocouples, but we are discussing the difference between the K Type thermocouples that normally come on kilns, and the S Type that is an upgrade if you order it when you order the kiln. The S Type thermocouple has several advantages. It will measure temperature accurately through thousands of firings. It does not wear out. However you can not just retrofit your kiln with one of these babies because you need to change a chip in the Bartlett Controller ($10.00), and you need different lead wires. It's cost is around $150.00 compared to a K Type at around $25.00.

However, Steve Lewicki of L and L Kilns recommends that you change the K Type thermocouple every time you change your elements. He says they are accurate for only a few firings and then they begin to drift. When I got my new L and L kilns, the thermocouples were protected from the atmosphere by a porcelain tube. After about 25 firings I took the thermocouple out of the tube and then tapped the tube on the table and there was a large pile of metal shards that had spalled off the thermocouple. No way that thermocouple was accurate.

So, bottom line is that S Type thermocouples cost way more when you get them, but they do not need replacement and they are accurate throughout their life. They are essential if you need to have any accuracy at all of your kiln's temperature.

I must say that they are easy to break and you must be careful with them. I take mine out of the kiln when changing elements, something I learned by experience.

Another thing that Kanthal recommends is using some kind of relay that is more sophisticated than just on and off. The idea is somewhat like that of a teenager driving a car with normal relays. The element is full on and then it is full off so it's like pressing the accelerator of a car full blast and then taking your foot off the gas full blast. This has the tendency to wear out the car, and it also has the tendency to wear out the element.

My friend Terry Fallon is designing an incredible kiln and it has solid state relays. They cycle on for 200 milliseconds and then they are off for 200 milliseconds. This has the effect of not shocking the element and also of not making the element get much hotter than the kiln. These relays are more sensitive and they need to be mounted on a heat sink so they do not burn up, but Kanthal suggests that they will increase element life.

Element Design --- Resistance (Part 2)

2009-05-27T22:23:00.004-04:00

So now we know that Papa Bear needs 67 amps, Mama Bear needs 55 amps, and Baby Bear needs 37.5 amps. From this we can calculate the resistance of the elements that we need to generate this many amps from the formula already mentioned, V = I x R.

So, for

Papa Bear, 240 = 67 x R and R = 3.58 Ohms

Mama Bear, 240 = 55 x R and R = 4.36 Ohms

Baby Bear, 240 = 37.5 x R and R = 6.4 Ohms

OK let's just look at Papa Bear here for a minute. The resistance of 12 gauge Kanthal A1 wire is 0.134 Ohms/Foot so to get 3.58 Ohms we only need 3.58/.134 or 26.72 feet of wire. Hey that's a very elegant solution and it won't cost much either. Just 27 feet of wire and we can fire the kiln. But there is a major problem and we need to understand what it is and what we can do about it. Just because it works mathematically does not mean it will work in real life.

Let's consider that our 27 feet of wire is a cylinder, where the diameter of cylinder is .081 inches -- that's the diameter of 12 gauge Kanthal A1 -- and the height is 27 feet. So we have a cylinder of diameter 81 thousandths of an inch and a height of 27 feet. The surface area of the cylinder is the circumference of the circle times the height of the cylinder. So we have .081 x 3.14 x 27 x 12 = 82.4 square inches of surface area. Note I had to multiply 27 times 12 so that everything is in inches.

So we have 82.4 square inches of surface area and we need to generate 16,000 watts of power so that each square inch of element must generate 194.17 watts of power. (16000/82.4)

The online Kanthal manual

(http://www.kanthal.com/C12570A7004E2D46/062CC3B124D69A8EC1256988002A3D76/D1D355F37C940491C12572B9003FD970/$file/1-A-5B-3%20UK%20resistance%20alloys.pdf?OpenElement)

would like for the watt loading figure of the elements to be around 15 instead of 194. That is, a good long lasting element will only have to generate around 15 watts per square inch of surface area.

My guess is that our 27 foot element would last only milliseconds with a full 240V passing through it.

Element Design --- The Three Bears (Part 1)

2009-05-26T18:07:00.005-04:00

Here is a photo of my 3 electric kilns. They are all built by L and L and I have found the company wonderful to deal with, and open to learning the special needs of crystalline potters.

I must confess that the kilns have names and they are Papa Bear, Mama Bear, and Baby Bear. It's kind of embarrassing to admit, but it does make identifying them much easier so the large one is Papa Bear, and so forth. Each kiln is 18 inches high and their diameters are 29, 24, and 18 inches respectively. The cubic footage of each of them is 6.7, 4.8, and 2.7, also respectively.

So the first question we have to ask is, "How much power do we need to fire these kilns?" There is a wonderful book by Robert Fournier called "Electric Kiln Construction for Potters" and it is full of information like this. Actually he gives 2 different tables, "Power/Volume Relationship in British Commercial Kilns," and " Power/Volume Relationship in American Commercial Kilns." The British table suggests more kW (Kilowatts) than the American table, and since we want our elements to last, I decided to use the British Table. The British table allots each kiln almost half again as much power, and since I want to power my kilns so that the elements do not have to work so hard, using the British table seems like the correct choice.

Papa Bear, which is 6.7 cubic feet will require about 16kW, Mama Bear at 4.8 cubic feet will need 13kW, and Baby Bear, at 2.7 cubic feet gets 9kW.

So now we need to know 2 simple formulas.

The first is Watts = Volts x Amps or W = V x I where I is the current in Amperes, V is the voltage and W is the power to the kiln.

The second is V = I x R where R is the resistance in Ohms.

For my kilns the voltage is 240 so this will remain constant throughout the calculations.

OK.

Papa Bear needs 16kW of power at 240 volts so 16,000/240 = 66.67 amps. We may not be able to supply that much because of the wire leading from the breaker to the kiln. But we will be able to improve on the 38 amps that the kiln was originally designed for, and which proved to be inadequate.

Mama Bear needs 13kW of power at 240 volts so 13,000/240 = 54.16 amps.

Baby Bear needs 9 kW of power at 240 volts so 9000/240 = 37.5 amps.

Tonight I lead the chanting in our Temple and I have to sign off for the moment.

But below is a photo of the inside of Baby Bear, and the double sets of elements. For some reason the hairpin turns offend my sense of craftsmanship --- I suppose it is the fact that the hairpin was not planned, someone just took the element and stretched it ---- and I am going to try to eliminate the hairpins.

Element Design for Electric Kilns

2009-05-25T06:08:00.002-04:00

I'm in the process of designing new elements for my 3 electric kilns.

For potters who do crystalline glazes, normal elements may last from 15 to 40 firings, and this means that we buy lots of elements, and that we spend lots of time changing them. But if an element is designed correctly, it will last for many more firings, and this was proven to me by redesigning the elements in my smallest kiln -- so far they have lasted 136 firings to cone 10-11.

This redesign was the inspiration of my friend Jesse Hull. Steve Lewicki of L and L kilns actually did the calculations and made the new elements. It was a redesign of the whole kiln, as we now have twice the element wire as before, and it is much thicker -- gauge AWG 12 to be exact.

The proper information to design elements is available online but it is much more complicated than at first glance. It's not as easy as it looks and you have to figure out basic parameters and then balance variables so that the elements work well. It would seem to be easy but it is not. However I am going to figure it out.

This information is really essential if you do crystalline glazes but most helpful if you are anyone who wants to maximize the life of your elements.

Before we get to the process of calculation -- and I admit that I do not have this all crystallized in my mind -- the most important variable is what is called watt loading. This is defined as how many watts per square inch of surface area do the elements have to generate. If they have to generate a lot of watts, they will not last as long. Bottom line.

I wish it were this easy. Just design the kiln with thick elements and all is well. But it is much more complicated than that. Thicker elements have less resistance per foot, so we now have to have a longer wire to have the same resistance as before, and that longer wire may not fit in our kiln.

I am going to try to figure it all out and post it here. Dull subject but of great value.

Gas Kiln Firing

2009-05-18T20:27:00.003-04:00

Today we unstacked the gas kiln which I thought was going to be a disaster. The firing was fine even though it was too hot in the bottom and I struggled to get it even while keeping the atmosphere steady. The lower half was about a cone too hot.

If you look very carefully you can see that there is a test tile which is very near to the left uppermost bowl. Too near as it turns out. I was able to remove it and do some work on the bowl, but it will always have a little mark.

Somehow I expect my pots to be perfect. I'm not perfect and MY body certainly has 64 years of dings and doinks and I accept (mostly) these. I have a chiropractor and a personal trainer to help with balance, flexibility, and strength because I realize that I need to address these issues of imperfection before they become debilitating. Why can't a pot have a little ding and that be OK?

At cone 012 that same bowl was also holding up the cone but I was able to move the cone with a metal rod.

There were some refired oilspot bowls in the kiln and this was the nicest of them, at least to my eye. The stoneware bowls are part of a dinnerware set for my friends Dean and Betty.

I also managed to drop one of the peephole hard bricks on the Oxy Probe and it broke the porcelain tubing but did not otherwise hurt the probe. It will have to be fixed before using it again. This was the result of the leather gloves having a hole in the finger and me using a tea towel to remove the brick, the tea towel catching on fire, and me not being aware enough to figure out what is happening.

I've been dropping stuff in the past week. Hopefully this is not the beginning of something permanent. I have to learn to be more aware.

It's time to take the burners apart and make sure everything is working correctly. The fans seemed like they could use some oil. I have 21 year old Dedell forced air burners and they need some attention, especially since this is spring, and mud daubers love to build nests in small orifices.

Detail Spray Guns

2009-05-15T21:56:00.002-04:00

Well everyone, Ginny Conrow, (www.conrowporcelain.com) uses a spray gun made by Iwata which lists for about 300.00 or so. I'm not sure of the price but it's expensive. I should have just gone out and bought one and forgotten about spray guns for life, but that would be too easy. Not my style.

So I went to Harbor Freight -- we have a new one in Gainesville -- and got a Central Pneumatic Professional HVLP Detail Spray Gun, Model 46719, for about 56.95. I used it and it was OK but I did not feel like it would keep me from wanting the Iwata. It's OK but not great and it seemed to get clogged by the glaze.

I went back there today because they have a very el cheapo spray gun, the Central Pneumatic Professional Mini Detail Spray Gun, Model 92126, for about 15.00.

It's not HVLP but I wanted to try it and when I got there it was on sale for 9.99. I got it home, hooked it up, and I just love it. It sprays smoothly and it resists clogging and it's easy to clean and it's kind of funky, but it really works well. Simple and direct.

So I will return the expensive one -- it's on sale now too -- and get a couple of the el cheapos and then --- well I still have to decide whether to get the Iwata. I mean it has to be better than some 9.99 knockoff, but how much better?

On another note, the gas kiln is stacked and firing. I had about 20 pots that did not make it which is disappointing.

Stoneware Glaze Firing on Saturday

2009-05-14T21:34:00.004-04:00

With any luck at all I will load the large gas kiln with stoneware tomorrow and fire on Saturday. Here is a group of mugs of which 8 will be included in the dinnerware set. Rather than making 8 or 10 mugs for a set, I like to make a whole bunch and not try to measure anything but the weight of the clay. That way there are some left over and I don't have to try to make sets, which I don't really like to do.

In this next photo there are some of the dinner plates and some sugar jars with lids, and four vases in the background. There is also a bisque porcelain wiggle jar and a large porcelain covered jar which I have not decided how to glaze. The shelves at front right are filled with boxes of test tiles.

Return to Thinking Out Loud.

2009-05-13T21:11:00.005-04:00

Sorry it has been several months since I have felt inspired to write anything. That's not because nothing was happening, but I was just in a very private mood.

Ginny Conrow (www.conrowporcelain.com) and I led a crystalline workshop at the Dunedin Fine Arts Center at the end of February which was very well attended and we all had a blast. We started work at 8 am and did not finish until 10.30 pm each day. We had the use of some of the kilns of the local attendees and did altogether 6 firings, I think.

I had a show at the Jacksonville International Airport for 3 months from January through April.

It's time now to get down to the day to day stuff of the shop. I am trying to finish a glaze load of stoneware to fire in the gas kiln. There is an 8 piece dinnerware set, some special order bowls, and I also have some oilspot items, which are being refired in reduction.

Last year in August I came up to John Britt's in NC and attended his oilspot workshop and have been smitten by them ever since; not that I was not smitten before. Here is my best one so far.

They are not as easy to do as they look, that is, if they look easy. It's one thing to get a nice glaze on a test tile, and quite something else to make that glaze work on a pot.

Even more Bentone EW

2009-01-10T11:34:00.002-05:00

I tried to get the batch of 300 grams of dry materials, 1 gram of Bentone EW, and about 4 tsp of CMC solution to work with 175 ml of purified water and it did not. The brush dragged on the pot. It's not that it was too thick -- it just did not work very well.

So I say that, for me, 200 ml of water is perfect for brushing this particular glaze on to this particular pot.

If you have a different glaze or clay, or bisque hotter or cooler, this will be slightly different for you but this is a good place to start.

The Bentone EW story continues.

2009-01-08T09:26:00.002-05:00

Yesterday I mixed a glaze with .33% Bentone EW and 200 ml of water. The exact specifics are 300 grams of glaze, 1 gram of Bentone EW, and 200 ml of water. I also added about 4 tsp of CMC solution.

It worked really well for brushing; in fact it was a little watery so today I am going to try to reduce the water even more -- probably 175 ml. The less water there is, the more glaze there is in the water, and the faster coats build up on the pot.

I'm still pretty amazed by how little clay there is in the glaze, how well it brushes, and how well it stays in suspension.

Ice Crystal

2009-01-02T21:41:00.005-05:00

Today I made some ice in the freezer of the fridge in the pottery shop and came back to find this ice crystal sticking out of the ice tray. It seems very curious to me that something like this would happen. How could this crystal grow an inch out of the water? I did have the ice tray full of water and that might have done something with the surface tension of the water so that this thing would grow.

Specific Gravity for Crystalline Glazes and Bentone EW

2009-01-01T20:14:00.006-05:00

Someone recently posted a question on the Crystal Forum about whether there is a perfect specific gravity for a crystalline glaze. My answer to that is that there might be, but I think this is not the best way to see the answer to the question, "What is the best, most efficient way to apply crystalline glaze to my pot?"

I think you have to take a look at all the variables, learn what part each of them plays, and go forward from there.

The first thing to look at is how are you going to apply the glaze. The conditions are different if you are going to brush the glaze rather that spray or dip it. I brush all my glazes and so the specifics here are going to be about brushing. But the generalities apply to spraying and dipping too.

Next you have the glaze itself and most crystalline formulas have very little clay which means that they are not really going to act very well no matter what, if you don't do something. But you can do something and the glaze will be fantastic to use.

I have been working with a material called Bentone EW and it looks like it is going to be the only clay that I will need in my glazes, and it also looks like the glaze will be really nice with only .5% Bentone EW. Imagine a glaze with .5% clay which stays in suspension and brushes well.

According to my friend Andreas Widhalm, Bentone EW is 10 times as powerful as regular bentonite. Bentone EW is what will suspend the ingredients in the water. It's much more powerful than Veegum T or Bentonite or Macaloid.

I mix up glazes in increments of about 300 grams dry materials. To this mixture I added 1.5 grams (.5%) of Bentone EW, dry mixed with a fork, and then added 240 ml of purified water and this made a very brushable glaze with the addition of some CMC solution. I think I can actually take out some of the water and have an even better glaze. Next time I will try 200 ml of water. I was able to brush the glaze on much faster than ever before.

One of the major points is that the more water you have in the glaze, the longer it will take to brush it onto the pot at the appropriate thickness. So, if you are smart, you want as little water as possible so long as the glaze brushes wonderfully.

Adding CMC will help the glaze to brush well. If you feel like your brush is dragging on the pot, you either need more CMC or more water. Again, according to Andreas, if you want CMC to thicken a glaze use it at a molecular weight of 300 or greater --- CMC with a molecular weight of less than 300 will thin a glaze. You really need CMC for brushability.

Finally for each different glaze you will need a measured amount of water, added CMC -- I make mine as a solution, and Bentone EW.

As an upper limit on the Bentone EW, I have a glaze with 2% EPK and 1.5% Bentone EW. I have added about 500 ml of water to get it to brushing consistency -- it also has a lot of CMC -- and I can brush and brush and nothing happens much except that the pot gets wet. Almost no glaze material shows up on the pot. I applied about 20 coats this afternoon and only got about .005" of glaze and that is not enough. I will have to throw that glaze away as it is useless. Its consistency is actually thick so don't let thick or thin fool you in how much water is in the glaze.

And I guess that's why I feel like specific gravity is not the right way to look at this problem. Specific gravity actually is used as a measure of solutions and a glaze is not a solution, it's powder hopefully suspended in water, which, I guess, makes it a compound.

I hope this helps. I would encourage you to keep good notes on how much water you have in each glaze batch, and how well that batch worked for you in application.

Christmas Carols

2008-12-25T06:39:00.003-05:00

Last night I led the Christmas Carols in the Temple and for some reason I had left my guitar in "G" tuning instead of standard tuning. So when it finally came time to start playing, something was really wrong. I strummed the first chord of "Oh Come All Ye Faithful" and it sounded terrible. My friend Mark Billman was playing the cello and I just looked at him like I was in deep trouble.

There were probably 75 people there and I was on the spot and at first I did not realize that I had chanted our daily morning hymm, the Sri Atma Gita, and that I always play that in this special tuning. So obviously I had to retune the whole guitar and it reminded me of one of my favorite poems, especially with so many people waiting.

The Guitarist Tunes Up

With what attentive courtesy he bent
Over his instrument;
Not as a lordly conquerer who could
Command both wire and wood,
But as a man with a loved woman might,
Inquiring with delight
What slight essential things she had to say
Before they started, he and she, to play.

Frances Darwin Cornford

Merry Christmas everyone.

Wieland Pug Mill -- Part 2

2008-12-22T21:24:00.003-05:00

Here are the rest of the pictures.

This is not a pugmill for someone who has no mechanical aptitude. I have had it apart and while I don't think that it will ever need to happen again, there is no guarantee. It is very, very sturdily built.

This should go to someone who does not need a whole lot of clay at any one time, but who wants and will appreciate really nice clay. Again this is not a good pugmill for a large production studio because it is very slow.

I am asking 2000.00 for it FOB Alachua, FL.

Wieland Pug Mill

2008-12-22T21:01:00.003-05:00

I have an old Wieland Pug Mill for sale and it will be an incredible pug mill for the right person.

It is a very heavy duty mostly stainless steel pugmill made by a small company in California. Charlie Wieland was kind of a genius/mad scientist who designed and built these pugmills and other pieces of pottery equipment. He is now retired. I think this one is from the 80's and I have had it since the early 90s. It cost 6500.00 when new.

It has a 2 hp motor and it's very heavy and powerful. The clay that it makes is, in my opinion, better than the clay that I have gotten out of both my Bluebird and Venco pugmills, and is the best clay that I have ever used. It's very compressed and throws very well. You can wedge it but you don't really need to.

The Wieland however pugs very slowly. When the 4 inch nozzle is on the pugmill, the clay comes out at about 12 inches a minute, so this is not a high volume pugmill. You get incredibly compressed clay but very slowly.

The pugmill is on wheels so that it rolls around easily. There was a vacuum pump that came with it but it stopped working really well and I bought a vacuum pump to replace it. It is virtually brand new.

The clay comes in at the top, is extruded towards the chamber, and then falls through the vacuum chamber and is finally extruded through a nozzle at the bottom. If you have a good vacuum, the clay is very compressed.

The augers are stainless steel and a material that Charlie called tabular alumina. I never got any rust stuff in my porcelain but there is one place where the clay could touch regular steel.

I could not get all the pictures of the pugmill in this one post so I will post the rest of the pictures in the next post.

Bison Tools

2008-12-18T20:57:00.002-05:00

It has been a long time since I have posted and the flu is one of the main reasons. It just has hung on for so long. Hopefully it is mostly gone. I do feel better and energy is returning.

There is also the fact that Christmas is just around the corner and I have not really done anything in the way of shopping. Fortunately I have been the target of some Christmas shopping but less than the last few years.

Ever since sometime in the 80s I have been using Phil Poburka's Bison Tools. Here is a photo of my first pair which lasted about 12 years. They are on their way back to Phil to have new blades put on them so they will be good as new.

The bottom photo shows what happens if one of these babies is dropped. Fortunately this one can be fixed, or at least I hope it can.

There is another one on its way that will not be able to be fixed and will have to have a new blade altogether.

These tools are expensive but they save so much time because they stay sharp even when working with porcelain. You can use them for years before they need to be sharpened.

See http://www.bisonstudios.com/

Thanksgiving

2008-11-27T18:37:00.006-05:00

Here at the Temple we have a vegetarian pot luck Thanksgiving dinner beginning at noon. Today the weather was beautiful and there were about 200 people in attendance.

I however, was at home trying to recover from a really nasty cold. With the Holiday Show next weekend I don't have time to be sick but yesterday and today was not a choice.

Tonight I draft a schedule and then try to keep to it so I can get everything done.

26th Annual Holiday Show Invitation

2008-11-24T21:30:00.004-05:00

I would like to invite everyone to our 26th annual Holiday Show. Directions are on the card.

Warm Throwing Water

2008-11-22T19:27:00.004-05:00

Here in north Florida we have already a few nights in the high 20s and one night in the high teens. A nice chilly morning, a nice chilly bucket of throwing water.

My solution is to put one of those coffee heater uppers in the water when I get to the shop, and by the time I am ready to throw, after my normal putzing around, the water is nice and warm.

Meghan is holding the coffee doo dad. Be sure not to let it get near the plastic of the bucket. I hang mine over a throwing stick.

Books for Crystalline Potters

2008-11-20T23:14:00.003-05:00

Finally the computer allowed me to copy and paste this information into the post. I had to switch to "Edit HTML" view, and then it just posts fine.

OK. Here are some of the books you want to own if you want to learn how to make crystalline glazed pots. I have them all and I think they are all important, but I would say that the first four are essential.

Don Holloway's book is also full of information and, if you are serious, you need this one too. (address: Crosscraft Originals, 18 Jana Dr., Monroe 71203; telephone studio (318) 343-9220 or (318) home 343-7658).

The last of these books, Nature as Designer, is not just about crystalline pottery. It is a book about inspiration and it has many photographs of wonderful seed pods and natural things that will really inspire your sense of form. It's out of print but you can find it and it is really nice.

Macro Crystalline Glazes by Peter Ilsley

Crystalline Glazes by Diane Creber
The Art of Crystalline Glazing by Jon and Leroy Price
The Complete Guide to High Fire Glazes by John Britt
Contemporary Porcelain by Peter Lane
Contemporary Studio Porcelain 2nd Edition by Peter Lane
The Art and Craft of Crystals by Don Holloway (Self Published)
Contemporary Ceramic Formulas by John Conrad
Ceramic Glazes -- The Complete Compendium by John Conrad
Glazes for Special Effects by Herbert Sanders (Out of Print)
Nature as Designer by Bertel Bager (Out of Print)

Main Street Pie -- a Pizzeria

2008-11-19T21:31:00.004-05:00

Our little town of Alachua has grown a lot in the 30 years that I have lived here. It used to be that you could not get any food at all but now there are a few restaurants, and a really fine place to get salad and pizza. It's called Main St Pie and it is run by the Langes -- pictured here are Brittany, Kristen, and Annette. They make a really fine pizza with great quality ingredients.

We were in for lunch today and you always leave full and happy. The atmosphere is very friendly and, by the way, they are less than one mile from I-75. So if you are going through Alachua, FL, and you have a hankering for a really good pizza, you know where to come.

Copy and Paste

2008-11-19T08:06:00.003-05:00

Whenever I try to copy and paste from an application on my computer such as Word or Pages directly into my blog, Blogger draws two lines below the text box that I am typing into now, and puts the text between those lines. There seems to be no way to get the text into the blog post without just typing it in.

Can anyone help?

Spodumene?

2008-11-18T18:13:00.005-05:00

A friend of mine gave me a bucket of stuff that was labeled spodumene when she retired from making pottery. The stuff looks like a gray talc -- I was suspicious of it and so piled up a teaspoon or so of it in the middle of this glaze catcher and fired it to cone 10 in oxidation. It's very brown and unlike what I hoped it would be.

I know that for awhile there were some high iron spodumenes going around. Could this be one of those? Any other ideas.

Alain Fichot

2008-11-16T05:54:00.002-05:00

Alain Fichot is a potter from France who is working with zinc crystalline glazes and the reduction process.

Click HERE for a link to a few slideshows of his work.

John's Photography Setup

2008-11-15T19:33:00.005-05:00

Here are a couple of snapshots of my photo setup. It has worked well for me for years and it's easy to set up and use.

The lights are strobe lights and they are bounced off the ceiling. Normally there would be large pieces of Foamcore between the lights and the pot, but then you would not be able to see what is happening. But it is important that the direct flash of the strobes be protected from hitting the pot to be photographed. It's also important that the lens of the camera not be able to see the direct flash of the strobe and this means even more ballasts of Foamcore.

The ceiling, in my case, is slightly magenta so it's important to set the "white balance" in the camera before shooting or the photos will be slightly magenta.

There is a frame hanging from the ceiling and it is adjustable because it's counterbalanced by four plaster cast Dixie cups which are suspended from the ceiling. The Dixie cups have round eye hooks cast in them so that they are easy to attach to the rope which supports the frame, and there are two eyehooks in the ceiling for each corner.

The frame is of 1 x 2, and there is Foamcore stapled to each side, and it is painted black and the edges are taped with duct tape. It's easy to move up and down.

Finally the background is Formica and it's a piece that started out 5 x 9 feet. These have to be special ordered but they allow you to photograph larger pieces.

Shipping FedEx -- Insurance Wake Up Call

2008-11-11T18:01:00.003-05:00

I just had a show returned from the Martin Museum of Art at Baylor University and there were two boxes with broken pots in them. These boxes were insured -- so I thought -- for the full value of the pots, but, in fact, FedEx will pay no more than 100.00 for a loss of porcelain pottery or other art works.

I ship with FedEx a lot. It's really easy to just come over to the computer and print out the labels and drop the package off at FedEx. I'm also a good packer having done it for almost 40 years so I have not known about this particular problem; It just has never come up.

But the person packing the show got some things too close to other things and the boxes must have really been thrown around, and here we are.

Here are some photos of just the inner box. It is a 16 inch cube and it was inside a 2o inch cube and well packed with peanuts and egg crate stuff. The first photo is of the box with the pot, the second of the box without the pot, the third is of the pot wrapped still somewhat in bubble wrap and the last one is just the shards.

So my question is what do you do about this? Do you have separate insurance? Do you ship with another carrier? Did you even know that you were shipping without any recourse to the full value of your work?

The pot, before it's last voyage, looked like THIS.

Possible Fronts for Holiday Show Invitation -- Part 2

2008-11-10T20:56:00.003-05:00

I want to thank everyone who took the time to comment on the Holiday Show invitations. I must say that the one person who did not comment was my wife Anne, and she did not think any of them were good enough.

So I spent a couple of hours on Saturday and another couple on Sunday photographing some new pots as possible images. The following two were the ones we liked and we decided on the first one last night because we felt that it sort of jumped out of the background. So we were done.

Except that today, I made an executive decision and decided to go with the second one. There is just something intangible about that pot that I like. It's one of the new satin matte glazes and I wanted to feature one of those on the cover.

Again, thank you for your help. Will this be any better? I don't know but things are quite peaceful around here.

Shelves -- For Michael Kline

2008-11-09T17:05:00.003-05:00

Since Michael is just finishing up the inside of his studio, I thought I would share a shelving system that has really worked well for my shop.

In the older days, you could buy at Lowe's a system called Spur Shelving, in fact that is what is shown in the photos. They sold uprights, brackets, and a few doo dads which we would mostly not use. These shelves are really strong -- will hold up hundreds of pounds and they are also very adjustable -- if you need to change the height you can do that instantly. The double holes for each bracket make them really seem sturdy. You can get the uprights in different lengths and the brackets in several different lengths too.

Today Lowe's sells a similar system and they are compatible with the old Spur shelving. They are similarly heavy duty.

You can buy something that looks much like this system at Home Depot, but it is not as well made and is not as heavy duty. It's not compatible with the old Spur shelves. It's slightly less expensive.

Lowe's also sells fiberboard shelves which are covered with melamine and these are what I am using in the shop for the most part. Before installing these shelves I always paint the fiberboard so that it's more water resistant.

It's a great system. If you ever have to move, you can disassemble them quickly and they don't take up much space. Nothing touches the floor. The whole thing looks very neat. It's not too expensive. They are really easy to install.

When I'm 64

2008-11-08T14:32:00.003-05:00

When I get older, losing my hair,

Many (nanoseconds) from now.

Will you still be sending me a valentine,

Birthday greeting, bottle of wine.

If I've been out till quarter to three,

Would you lock the door?

Will you still need me,

Will you still feed me,

When I'm 64.

..........

Sorry for this little indulgence but it only happens once in a lifetime.

And my friend Marsha Silverman, who makes the most wonderful porcelain pots, is 65 today.

Porcelain Clay Body

2008-11-07T18:56:00.006-05:00

Back in the late 80s I was working with Miller 550 porcelain and it worked very well for me, except one little thing. It's really a cone 9 clay and if I trimmed too thinly near the bottom of a medium sized piece, it would sag if I fired it hot, which I usually did.

I contacted Karl Miller, who was at that time involved in the daily operation of Miller Clay, and he suggested Miller 570, a clay with higher firing temperature but still based on Miller 550. It was a step in the right direction, just not a large enough step.

So I asked Karl to help me design a porcelain formula which could be fired to cone 12 without sagging, but still based loosely on 550, and this is my final iteration, some 20 years later.

Porcelain Formula

Grolleg 55

Custer Spar 15

200m Silica 28

Bentolite L 1.5

VeeGum T 1.5

Plus add 44 grams of Epsom Salts dissolved in hot water for each 100 pounds of dry mix.

I do not know the amount of water that is added to the formula, but if I were making it myself, I would determine the correct amount of water. And it would be pure water.

Notice how this clay differs from the so called "Equal Parts Body", which is 25% each of Kaolin, Ball Clay, Silica, and Feldspar. It has way more clay, more silica, and less feldspar.

My celadon glaze, the 4, 3, 2, 1 glaze from Leach, does not craze or shiver on this body.

Possible Fronts for Holiday Show Invitation

2008-11-06T21:54:00.003-05:00

Here are 4 possible fronts for my holiday show invitation this year. I would like to know which one you think I should send out.

Thanks.

Lead Based Crystalline Mattes

2008-11-06T21:07:00.003-05:00

Here are some of the lead based tiles I got out of the kiln yesterday. I plan to also post fire these in the large gas kiln in the next week or so.

To me, at this point, the glazes do not have enough contrast between the light and dark and hopefully this post fire reduction will help them along a bit.

Right now I am working on 2 different kinds of matte crystalline glazes. These, which feature a lead based frit, and the satin mattes, which are softer and more sensual to the touch. I really like them both.

Glaze Micrometer in Action

2008-11-05T17:26:00.003-05:00

Here is a photo of the glaze micrometer being used to measure the glaze on a test tile and giving a reading of almost .0017, or seventeen thousandths of an inch.

You can see how the plunger rests in the pad of my finger - It's right up above the 25 on the gauge - I'm using pressure to hold the needle against the clay body as the shoe rests on the top of the glaze.

The knurled knob that you can see closer to my palm, is used to set where the needle is with respect to the background. As the needle wears down you have to make this adjustment.

I have had this thing apart to work on it and it is really a very nice machine. Nothing about it is cheaply done.

Glaze Micrometer Revisited

2008-11-03T20:31:00.004-05:00

I would like to address some of the comments on the original Glaze Micrometer post.

First of all, when you are doing crystalline glazes, or any other type of glazes, the thickness is really important, but particularly for crystalline and other "art" glazes.

You can buy a Starrett 643JZ at MSC Industrial for 319.97 and there are 35 in stock. You will have to grind the shoe down to a size so that it sets on top of the glaze -- mine is 3/16" x 7/8" and Bill Boyd's is 1/2" x 1/4" so it is not absolutely set in stone what size the base of the shoe needs to be. Mine does not work well on the inside of bowls and Bill has fashioned his for that purpose.

You have to keep pressure on the needle while you read the thickness on the pot or tile. I had hoped to get a picture of this today but no one came into the shop to visit -- and press the button on the camera while I make the measurement. I will try to get a photo tomorrow. I do have a way to let the top "thingy" that you press down rest in the middle knuckle of my index finger so that it keeps the pressure on naturally.

You also need to get a reading just after the glaze is dry enough so that it won't come off. You can wait 5 minutes but if you wait an hour, the reading will be off because the glaze will have dried, and it will be thinner.

This tool is nothing like a hydrometer. If I understand correctly, a hydrometer is a tool that you put into a solution and it measures the specific gravity. The problem is that glazes are not solutions, they are mixtures of chemicals and water, and maybe electrolytes too. So while the hydrometer can be helpful in that you can, if you use no electrolytes, measure the amount of water to the amount of chemicals and get that right every time, what if your water changes? Say all of a sudden your well water has lots of sodium. Your hydrometer may not give you the answer you want.

Most glazes that are used by crystalline potters need to be adjusted with either CMC, a flocculant, or both. The hydrometer does not seem like a good tool for this purpose.

There is another way to measure the amount of glaze on a pot and it is used by industry a lot. They just measure the surface area of a pot and put on a specified amount of glaze, so you might see the amount of glaze expressed in grams/square inch. My friend Phil Hamling, uses this method and you can see some of his efforts Here.

If Burlon Craig could read the glaze thickness from a shard, and I'm sure you could get that good, he would also have to make the interpolation from a wet glaze to a dry one. The shard is dry and the glazes are wet. The early folk potters were really in tune with their materials.

My friend Darrell Adams, who is the grandson of Bill Gordy, told me that he used to go out to find materials with his uncle DX and DX would tell him about the spirits in the rocks. I bet DX did not have a glaze micrometer.

However, that doesn't mean that I don't need one. It's been a very powerful tool for me.

Crystalline Matte Test Tiles

2008-11-02T06:39:00.004-05:00

Here are a couple of crystalline matte test tiles which just came out of the kiln this week. I plan to refire them in a post fire reduction in my large gas kiln but wanted to get a nice photo of them as they are before post fire reduction.

Just recently, I've been labeling my glazes with a number and a letter so that glazes are called 0-A, 0-B and so forth. It would be more efficient to use letters for both -- A-A, A-B, ... but I started this way and was too far along to change. Instead of running out at 256 combinations, you would have, by using all letters, 676 combinations before you have to add a digit.

The mixing notes are carefully kept in order so that all I need to write on the bottom of a tile is the number-letter and the thickness of the glaze. So a tile might say 1-R 15, which means it is glaze 1-R located in order in the notebook, and the thickness is .0015, as measured by the glaze micrometer. After the tile is fired, I write the firing it was in on the bottom in permanent marker. The kilns are hooked up to my computer by a program called KISS, and so the firing cycles are named and duplicable. And I keep the cones in a ziplock bag for reference.

Probably waaaay more than you want to know.

26th Annual Holiday Show, Dec 6th and 7th 2008

2008-11-02T06:22:00.004-05:00

Our 26th Annual Holiday Show is just 5 weeks away and I am busy making some utilitarian stoneware. While I mostly concentrate on porcelain and crystalline glazes, making stoneware is an opportunity to go back to my roots and make some things for customers who may not appreciate the porcelains. Stoneware clay is also a fine break from porcelain.

Here are some bisqued mugs and bowls -- and some porcelains in the background. I really have a lot of throwing to still do and the time is short, as always.

Terrified of Writing

2008-10-30T19:08:00.004-04:00

As a freshman at the University of Florida in 1962, we had to take a reading and comprehension test and I made the 15th percentile of all freshmen. I had not written much in high school and I did not want to write much in college either so I majored in Electrical Engineering. We had to take subjects like Humanities and American Institutions which required a lot of reading and I struggled mightily with those. I just could not read fast enough and my comprehension was terrible. I was determined to not write any papers in college -- quite stupid as I look back on it, but this was a real fear for me and I gave in to it.

My first course in Electrical Engineering was early proof that I was not going to be a successful engineer either so I switched to Math, a subject that I was good, very good, but not great at. I did make it through college without writing any papers and stayed for graduate school in Math. I took every course but one for the PhD but somewhere in here I discovered Ceramics, got my Master's degree in Math, and began to study Ceramics. I did have to write a Master's thesis -- On the Structure of Pre-P-Rings -- a subject that I could not tell you one thing about today. Well maybe one but not much.

I went to graduate school in Ceramics at The University of South Florida in Tampa and got an MFA in 1972. I had to write a thesis -- Some Structural Possibilities for Smoked Raku -- and so I got 3 degrees writing only two papers. Ten years of college -- combined writing under 40 pages.

As I look back on this attitude I find it to be incredibly short sighted. It's very difficult for me to sit down and express myself and organize my thoughts in a cogent way. I also struggle with organizing my workday and the overall management of my time. It's about seeing the "forest" and the "trees" at the same time, and I tend to see one or the other, but not both. I think the two things -- that is: the inability to write and the inability to manage my time and resources -- are linked to a place in the mind which is just underdeveloped.

My wife Anne has a degree in English -- actually the subdegree is called "Creative Writing and Linguistics" from UF here and she is quite a talented writer. See an Example. She is also a good organizer and manager.

This blog is my first attempt to overcome this shadowy past. Hopefully the writing will improve as I become more practiced. But mostly I hope to achieve a new level of organization and consciousness through written expression.

Tapping to Center

2008-10-29T19:59:00.003-04:00

Tapping to center is something every potter should know how to do. It was taught to me by Steve Jepson when I was just a sprout. It's easy to learn. In fact many of the people who have worked at the shop have learned it and they were not even potters. Here's how to learn it.

Take a coffee can and fill it with about 1/3rd sand. Get a bat with some sort of foam or a bat with something that will offer friction like surf board pads. Place the coffee can on the bat, start the wheel slowly, and start tapping the can with your left hand (if you are right handed) until it goes to center. Then place it off center and start tapping again until it gets to center. At no time are you to try to understand with your mind where to tap the can. You just tap it and when it gets to center you move it off and start again. Do this for 5 or 10 minutes and then stop. Do this every day for 3 weeks and you will be able to do it like a pro.

The reason you want to use your left hand is that you will have a trimming tool in your right hand and you don't want to have to put it down.

Tapping to center is way more flexible than using say a Giffen Grip. A Giffen Grip is a very useful tool and I would not want to be without it -- I use it to trim mugs when the bottoms are too soft to hold at center after tapping, but tapping to center is so versatile and quick that it is the best solution the vast majority of the time. It will save hours in the course of a year for almost anyone who makes pots.

Say you have a pot which needs to be trimmed in a chuck. (I sign my chucks "Charles" because they are very formal). You tap the chuck to center and then place the pot in the chuck and make sure the bottom of the pot is horizontal and then you have to center again because the chuck is not quite round and neither is the pot. So you tap the chuck to center again. It's not the chuck that you center but the pot.

Now you can trim the pot and if something goes off center you can just tap it back.

Katy Rush to SOFA

2008-10-26T22:19:00.001-04:00

This afternoon Katy brought another of her sculptures to be fired. She doesn't have a kiln down here yet and I'm firing a kiln load for her. They are going to be shown at SOFA in Chicago -- Katy leaves next week to drive up.

This last one is going to have to dry for a few days -- it's much better to move them at this stage of drying than when they are absolutely dry.

They are hand built porcelain with no glaze.

Jeff Zern to Berkeley, CA

2008-10-25T06:48:00.004-04:00

Yesterday was Jeff's last day working here. He has been helping me the last few weeks and has been invaluable. He is very thoughtful and methodical in his approach.

He is a very talented ceramic sculptor with a degree in Ceramics from the University of Florida and he is moving to Berkeley, CA next month after a time with his family in Pensacola, FL.

He wants to work and check out graduate schools on the west coast. If you are in Berkeley and need help here's a guy who works hard, is fun to be around, and is serious about clay.

According to Jeff, "There is no strong coffee, only weak men." He takes his black.

Glaze Micrometer

2008-10-23T21:54:00.003-04:00

It's also important in glazing crystalline pots that the glaze thickness be checked as the glazes are very sensitive to how thickly they are applied. My answer to this problem was to take a Starrett JZ 643 Dial Depth Gauge and modify it so that it works as a measuring tool for checking the thickness of a glaze. The base of the shoe is 7/8ths of an inch by 3/16ths of an inch. This gauge will measure the thickness of a glaze to the nearest half thousandth of an inch.

To use the meter you press the button on the top and a needle like point comes out and you stick that point through the glaze until it hits the bisque and then, while still maintaining pressure on the point, you allow the bottom of the shoe to rest on top of the surface of the glaze.

This is one of my most valuable tools. I would not glaze without it.

Yawn

2008-10-22T22:10:00.001-04:00

My friend Bill Schaaf took this picture of me in a full yawn. I'm about that tired now. Time for bed.

Mixing Glazes for Brushing

2008-10-22T20:14:00.000-04:00

One thing that crystalline potters must be aware of is that certain crystalline glazes do not store well. If they are zinc oxide based, they could develop actual crystals in the wet glaze in just a couple of weeks. These crystals change the formula of the glaze and make it not so good.

So it's prudent to not mix up too much glaze, especially if you are working alone or in a small studio. When you are only mixing up enough glaze to apply to the pots immediately, the problem of how to apply the glaze comes up. Basically it comes down to whether you want to brush or spray your glaze. For many reasons, I decided to brush the glazes on my pots.

So what is the best way to prepare that glaze for brushing? It's pretty complicated but I'll try to explain it here and also let you know that I am still tweaking the process. Here is how I mix up 300 grams of glaze, my normal amount.

Be sure to wear a mask and rubber gloves. You can get the purple ones at Sam's Club for cheap and just throw them away every time.

Add the dry glaze ingredients to a one quart yogurt container. Be sure to have a check off system so that you don't make a mistake. I always make a check mark on my glaze mixing notes when the yogurt container that I am using to weigh the chemicals is on top of the yogurt container that is holding the glaze. That way I know what I have done and the materials have a chance to settle a little. It's good to have a slight breeze away from you too.

When you have all the ingredients in the container take a dry heavy duty plastic fork and stir them until they are homogeneous. You don't have to go overboard here, just make sure you don't have large clumps of single materials.

Add a measured amount of pure water. Don't use tap water as it will change over time. I usually add between 250 and 300 ml of water to the glaze, but this will depend on how you like your glaze. All I am saying is that water is one of your glaze ingredients and you want to know how much you are using so that when you get it right, you can add that amount each time.

Allow the glaze to sit for a few minutes so that the water can penetrate the dry ingredients.

Add about 3 tsps of CMC solution.

When I mix CMC I put hot water in a blender and add CMC powder until I can't add any more -- the powder is not going into solution. I let it blend for a minute or so and then pour it into yogurt containers and let it set for a couple of days until the clumps dissolve. My solution is kind of thick -- not real thick like honey but sort of thick like maple syrup.

Mix the glaze with a hand blender until you have dissolved all the clumps and it is ready to pour.

Pour it through a 100 mesh sieve and then back through the sieve into the original container, which has been washed out so that no granular stuff is still there. So you sieve it twice.

At this point your glaze should feel somewhat watery because you have deflocculated it with CMC. You don't want to leave it like this or it will settle.

Bentone EW is a suspender that works much better than Bentonite or V-gum-T or Macaloid. I got some years ago from a paint chemist and I do not know where to get it now. I'm still playing around with the amount to add to the glaze but today I added one gram of Bentone EW to 300 grams of glaze and it thickened it and suspended it a lot. After adding the Bentone EW you have to blend it into the glaze and let it sit for at least a half an hour.

If the glaze seems perfect then you are done. But I usually add a few drops of Calcium Nitrate solution to help with the fluidity of the glaze. You will again want to use the hand blender (I just got three of them on sale at Macy's for 19.99 each).

If you get the right amount of Bentone EW you don't need the Calcium Nitrate solution.

At this point, your glaze should be ready to brush. You may have to adjust the water so that the glaze is to your liking.

Mixing Calcium Nitrate:

Add 5 pounds of Calcium Nitrate pellets to a gallon of water and blunge until the pellets are in solution. There is all this crap in the mixture and you have to get it out somehow. Some you can get off the top and some you will have to wait until it settles and then take the clear off the top. It will take you a few days until your solution is totally clear. You just keep decanting the clear. I have tried pouring it through coffee filters but even the very fine stuff -- probably EPK -- goes through.

Lap Wheel

2008-10-21T21:25:00.001-04:00

Today we prepared pots for a post fire reduction.

The first thing you have to do is fire the pot in it's normal firing and this one just came out of the kiln this morning. After separating the pot from it's pedestal and catcher it is wet ground on this lap wheel until the bottom is smooth and the glaze which might be on the bottom is gone. This is quite easy with this tool, which is actually a Crystalite Crystal Master Pro 12 with a 120 grit diamond pad. It is a wonderful but expensive tool -- if you do a lot of grinding of crystalline glazes, this baby will save you an enormous amount of grief and time.

We have the kiln loaded and candling for the firing tomorrow.

Lennie Kesl

2008-10-19T14:49:00.000-04:00

I have been making collaborative works in red earthenware with my friend Lennie Kesl for over 28 years now. For a time we both taught at Santa Fe Community College in Gainesville and one day I asked him whether he wanted to paint on some pots and he did. Here is Lennie at the ripe young age of 82.

This is one of the platters from the last batch. It's about 25 inches in diameter and is glazed with underglazes and glazes, used in Lennie's somewhat unique manner. He doesn't know anything about ceramics so he just uses the materials like paints. He might have an underglaze a half inch thick, or he might take dried up underglazes and crush them into little pieces and build little mountains. He really loves the glaze crystals that you get from Amaco.

During the time we were working on this series of 8 platters, our friend Rusty Hammer was making a video and you can watch it by clicking here. It's called Making Plates.

Pottery Shop

2008-10-19T06:30:00.000-04:00

I have lived in a spiritual community north of Gainesville, FL since 1978.

This building has been my workspace for over 30 years. It was originally intended as a storage place for a construction company and I was given a small space in the corner, but over time my "Empire" expanded to include the whole downstairs.

When I first moved to the community I lived upstairs in a small room. Everything I had could fit into the back of a pickup truck. It's not like that anymore. I still like to keep my stuff to a minimum, but it would now take a semi to move the shop.

If you look to the right you can see the kiln room out back.

Porcelain -- My Favorite

2008-10-18T22:55:00.000-04:00

Here is an example of the porcelains. This is a pot that was fired in the gas kiln and reduced during the final growth cycle of the crystals. It's not a type of firing that I do often because my kiln is not quite suited for crystalline glazes. Kilns for crystalline glazes are ideally nimble, and my gas kiln is anything but.