Monday, April 19, 2010

CLAY INTO GLAZE

As I throw, I tend to throw as close to the actual form I am after as is possible. What this has done, it allows me to minimize the amount of clay I trim off my pots, excepting inside the foot ring. I happen to love a pronounced and deep foot ring, so some scrap clay is inevitable.

After 20 years of throwing and making pottery in general, the process of reclaiming scrap clay has become both tiresome and troubling for my wrists. Enter a flash of inspired lunacy born of an over fired kiln. Back when I started learning pottery, I got to see first hand what happens when a terra cotta bisque goes up to cone 6 or so. The one time pots became a molten flood of attractive frozen liquid. This lead me to think about processing my scrap into glaze. I have always used my terra cotta and porcelain scrap to make slip, but this seemed like a simple way to lessen the amount of wedging I would have to do and a natural progression of things.

After a series of intensive tests and line blends, I ended up crafting a durable and attractive base glaze out of my terra cotta scrap and a small amount of frit. This base glaze has become my amber, temmoku, medieval green, haiyu ash and Ao glazes. I have further fine tuned the glaze and now calcine about 20% of the volume at 1600 degrees to stop crawling problems, which has all but gone away.

As for my porcelain scrap, I now use it to make my neriage base, based on a technique I learned from Judith Salomon at the Cleveland Institute of Art. In her hand building, she would pour out slip on plaster to make slabs. I used the same principle, I dried the scrap, slaked it down and poured it into old fruit juice bottles (plastic) and then added colorants to make colored clays to add to white porcelain and suddenly, easy neriage. I would pour the colored porcelain slip onto plaster, let firm up and then cut it into strips which I will later used wedged into the porcelain. Far less wedging involved.

This may seem like an insignificant achievement, but for me the 50% or more reduction of wedging has slowed the damage to my wrists and elbows as well as coming up with some interesting neriage, some great fitting slips and a handful of durable, practical and attractive glazes that compliment my forms. A win-win in my pottery book.