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

[Heidi Maiers]

That is strange indeed. What I would want to find out then, is if the clay that you used was actually the clay that you thought you were using. As in a packaging error at the factory and the wrong clay was put in the box you bought. If it was actually a cone 5 clay, that would explain 2232 being too hot for it and also the fact that the color outcome was not even in the range listed for that clay - not to mention the excessive shrinkage, and the too high density. If you bought a 50 pound box, the two bags may or may not be the same, but to be safe, like you say, the next one I would definitely have fired in the 06 range. I have fired as low as cone 018 with great results on a cone 10 clay.

I agree with you about the grog issue - it is easy to overwork the surface with water and bring out too much grog. This is something I've been trying to work on myself since I use a high grog content clay so I can fire them without having to hollow them out.

At any rate, I'm sure you've learned a lot with your first ceramic piece and the next one will be much less frustrating and even more beautiful - if that is even possible.

[Garth Herrick]

Heidi,

I forgot my own method of smoothing. Now I remember: I made a grog free slip from some of the clay and carefully painted it on layer by layer with my best sable oil painting brushes. This I tooled and rubbed with some water until some grog began to surface. Then I would let it set up and dry more and repeat the process until it all looked sufficiently cohesive. I spent a lot of time doing this. The more I refined, the more I found that needed further refinement.

I'm a painter, so naturally I found a painting approach to sculpting. I used all types of paint brushes and found brushing around the clay to be very effective for rapidly cleaning up rough modelling. This was especially true for the ears, nose, and mouth, etc. The ears just appeared like magic, just as if I were modelling paint on a canvas portrait.

Finally the deadline came up, and I had to keep it in a toasty warm place to fully dry for several days. It was at that time when the brown clay fully dried to a light gray, that I took all the photographs. It was fired the next day.

Garth

[Heidi Maiers]

Garth,
That's a very innovative and logical approach - one I would almost expect from such a refined painter. While refinement can become an addiction with sculpture, your piece does not look overworked at all - in fact, your method of adding slip definitely helps the skin look more lifelike and fleshy. I would almost worry about the slip sealing the "pores" where the gases escape through the grog. When you say there was some cracking, was this limited to just the surface, or did the cracks run deeper? I am assuming the cracking occured during the firing and not before while it was drying. There doesn't appear to be any blistering between the slip and the main body, so you did a great job addressing the cohesion issue.

About that strange variegated yellow color - could it be that the brushes you used to mix and apply your slip still contained a touch of paint pigment? If so, that would explain it.