Monday, March 14, 2011

New Drying Molds

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.


John Bauman said...

What an interesting process. Probably yields the most quickly plastic clay of any process since filter pressing.

JoAnn F. Axford said...

How much clay do you make at a time?

John Tilton said...

Hi JoAnn,

I make about 100 pounds dry porcelain and just a little more than that in stoneware. I only have a small blunger so it does not mix up larger amounts well.

It does make good clay and I like the process, but if I made more pots, it would not work very well. It takes a lot of space.

deanandmartinpottery said...

This is a pretty fast way of drying really wet clay out quickly and evenly. I think these molds are great the way they turn up so it doesn't let any spillage happen on your floor. Your pots are wonderful. Keep up the incredible work that you do because it is such an inspiration to all potters. Thank you!

John Tilton said...

I made these guys with about a 3 inch bottom and 2 inch sides so when the clay pulls away from the sides, there is still lots of drying power left in the molds. They are a good way to reclaim slip for me. I put folded sheets in the molds before pouring in the clay so that it can be removed more easily and so the molds do not get too saturated.

I still have two bags of plaster so it looks like we will make two more when Josh comes out on Friday.

It is a very easy process but it does take space to make the clay and store the molds.