thebeerbaron

Things have been quiet on the blog front as I hit the sketchbooks, but finally I have some updates for you.

I got my tail in gear today and wandered over to [URL="http://www.sculpt.com/"]The Compleat Sculptor[/URL] to pick up some clay. I picked up two 1.75lb blocks of "Chavant Y2 Klay".

I'm used to working with what are called "water-based" clays - the kind of stuff that people used to dig out of the ground, lump into a vague vessel form, and throw into a fire. Your mugs, bowls, and china service are made out of this stuff. It's easy to work with for the most part, but in order to be stable it has to be dried, then fired in a kiln. The clay shrinks during this process and can warp a bit. And once it's dry, you can't change it at all. It's done.

The clays used for design work are different, non-drying, non-shrinking clays. I've never worked with them before, so there'll be a bit of a learning process here. The first problem is that whereas I usually build my clay sculptures out of pure clay, the cost of doing that with this stuff would be too much. Instead the typical practice is to build an armature out of something else, in my case foam core board. I'll build a very rough approximation of my design using these boards, then smoosh this clay on top and carve away until I get the right shape.

Another major difference is that the Y2 clay is very, very hard at room temperature. Water-based clays are completely malleable at room temperature - what makes them keep their shape is the actual drying process. This clay doesn't dry, so instead you have to use heat to make it workable. By pressing hard on the edge of one of the clay cylinders, I could get it to deform, but otherwise each stick of clay was hard as wood. Hmm.

Here's a picture of what the clay looks like before I started working with it. US quarter for scale.

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Since I didn't get a chance to go to the craft store today I couldn't start on my design so instead I tried to figure out how to work with this clay. The helpful technician at the sculpture store said I could heat it up with a lamp, so I tried that. I don't have a spare desk lamp just lying around - there's just no room. In fact, I only have one lamp in the entire apartment. So I grabbed the lamp off my end table, took off the shade, leaned it against a sculpture and tried warming the clay that way.
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("Thank You Bob", stoneware, 2010)

This had only minimal effect. The clay becomes workable at 145F, and the 60W bulb eventually got the corner closest to that temperature, but it would never have warmed the entire brick.

The next great idea was to turn my toaster oven on low and put the clay on top of some tinfoil on top of the hot oven. After playing with the oven temperature a bit, I got the clay to warm up, but it was just impossible to get enough heat into the brick that way. At lower temperatures the outer edges of the brick got warm, but the opposite side was stone cold. When I brought up the oven temp, the clay melted.

The idea that finally worked was to fill a large bowl with hot tap water. The stuff that comes out of my tap is in the 130F range, perfect! I sealed a half-stick of the clay in a Ziplock and immersed it in the hot water. After about 20 minutes and two water changes, I had something I could work with.
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I think in the future I'll heat the water up with the microwave to get it even warmer, but it was generally a very good way of heating up the clay. Water is a great thermal conductor! I may have to invest in a heat gun to move the clay around once it's on the armature.

The next step is to build that armature. I need to put in some time at the studio tomorrow, working with my "normal" clay, but after that I'll stop by the craft store and pick up some supplies so I can work on the form next week.

I realize this isn't particularly car-themed, but I hope you're enjoying a look at how this clay stuff works. I think you'll get to see some pictures of the armature and the initial application of clay. After I start working with it though, no more peeking!