Greetings from Philadelphia

[Garth Herrick]

Heidi,

There was about a one inch radius semi-circular glass surface on the front face of the square base rising from the bottom center. It had almost a bottle gray green color. 2232F is the temperature, that was registred, and all at the store agreed this clay body should have been perfectly stable at cone 6

To smoothe the surfaces, I tried not to overuse water, because it would subtly erode the surface and expose too much grog, for my liking. I did a lot of tooling with wooden tools and used my fingers a lot. I suppose the natural oils in my skin had some effect. There was quite a motttled range of surface color, which I did not mind. I just did not expect the overall yellow cast that had no relationship with the store samples. Also my sculpture was far less porous and absorbent of water than the cone 6 sample, which also suggests a temperature discrepancy.

I asked the clay manufacturer how a specified shrinkage rate of 12 1/2 % could become a documented 18% in my case. They offered no clue, saying they never test their clays beyond their design limits, and did not want to jeopardize their relationship with the store that serviced me. The store sent them a sample from my firing for scientific analysis, but there was never any findings response.

Thanks for your input, Heidi!

Garth