Foam 2.0

In a previous hypothesis, I looked to the Stull chart to make cone 6 clay bodies with similar shrinkages and different colorant agents. Within this line of inquiry, I found the ratio of alumina to silica had less to do with shrinkage than anticipated, but discovered a foaming clay. This specific chemical make-up led me down a rabbit hole in terms of ceramic composition; however, when starting my research at STARworks, I wanted to challenge the color of the foam. Could the clay deposits found in North Carolina be the source of color in a foaming clay? How would the atmosphere change the tests due to the amount of iron in the deposits?

Being in North Carolina, I was suddenly exposed to local high temperature clay. Even though I had previously dug and processed the shale found in Alfred, NY, this process was completely new – no need to ball mill it, embrace the gritty texture they said. I had never seen so many different colors of dirt in the same place, and it was all local. Most of the deposits tested vitrify hotter than cone 10, and STARworks specializes in making these clays more user friendly for customers. Felspar is added to recipes to drop the temperature for instance. This got me thinking.

By completing triaxial blends of each of the 7 clay deposits found in the area combined with talc and feldspar, the goal was to create the foaming clay by adding different ratios of flux. If the clay could be melted and utilized as an alternative texture component for patterns via slip, then the contrast of the work would be dramatized in feel and color. If the clay content of the test was high enough, the plasticity of the material could make for producing handles and other additive components – less decorative and more architectural. 

After mixing the recipes for the tests, I fired the 7 different triaxial blends 5 different ways with the type of firing being the constant variable. Below is a key to the photos revealing the results. While the x axis refers to the clay deposits, the y axis refers to the type of firing.

Catawba ^04 – oxidation	Cameron ^04 – oxidation	Candor ^04 – oxidation	Mitchfield ^04 – oxidation	Lyllsville ^04 – oxidation	Okeewemee ^04 – oxidation	Gowling ^04 – oxidation
Catawba ^6 – oxidation	Cameron ^6 – oxidation	Candor ^6 – oxidation	Mitchfield ^6 – oxidation	Lyllsville ^6 – oxidation	Okeewemee ^6 – oxidation	Gowling ^6 – oxidation
Catawba ^10 – oxidation	Cameron ^10 – oxidation	Candor ^10 – oxidation	Mitchfield ^10 – oxidation	Lyllsville ^10 – oxidation	Okeewemee ^10 – oxidation	Gowling ^10 – oxidation
Catawba ^10 – wood/salt	Cameron ^10 – wood/salt	Candor ^10 – wood/salt	Mitchfield ^10 – wood/salt	Lyllsville ^10 – wood/salt	Okeewemee ^10 – wood/salt	Gowling ^10 – wood/salt
Catawba ^10 – gas reduction cool	Cameron ^10 – gas reduction cool	Candor ^10 – gas reduction cool	Mitchfield ^10 – gas reduction cool	Lyllsville ^10 – gas reduction cool	Okeewemee ^10 – gas reduction cool	Gowling ^10 – gas reduction cool

Though the main goal for these tests was to find a foaming clay, the triaxials primarily resulted in glaze recipes. I mixed a couple of them in larger batches, and due to the iron in the clay, these glazes reacted differently when exposed to varying amounts of reduction. Because iron fluxes more in a reduced atmosphere, the clays with higher iron content melted more than clays with less iron. These same ratios acted more as a foam in the oxidation firing. 

When applying these results to some work, the glazes were more predictable than the foaming clay. I attempted to make some handles, but the forms slumped during the firing. These components needed more support and could not very well stand alone. While some of the foam looked appealing as a button test on the triaxial, brushing the same recipe on as a slip did not work as effectively in my opinion. Applying it really thick is most ideal and comes off as more intentional – less like a glaze defect. 

Because the testing took an extensive amount of time, I did not have the chance to apply the results as much as I’d have liked during my time at STARworks; however, texting the clay in this manner helped me to understand the properties, and I enjoyed processing the material myself. The idea of the color agent being local is appealing to me as a maker even if I can’t quite connect it conceptually. How many different ways can one rock be used to create a different texture, color, movement within a work? How can the application be stretched in future works? Questions such as these push me forward as I continue to make.