Sunday, June 23, 2013

Cold Porcelain

One of my major build projects for this year's Origins was a giant sized custom Settlers of Catan board, with a Cthulhu theme. I call it, Cultists of R'lyeh. Nineteen hexagonal tiles had to be hand sculpted with varied terrain. I needed a sculpting medium that was easy to work with (as my sculpting skills are very meager), dried hard without baking, and was very cheap, as I would need a lot of it. After a little looking around on the web I came across cold porcelain. It is a home made air dry clay that is super easy and cheap to make. I found several recipes for it, everyone seems to have their own favorite way of formulating it, but the one I used is made from  
  • 1cup of corn starch (powder), 
  • 1 cup of white glue, 
  • 2 tablespoons of mineral oil, 
  • 1 tablespoon of lemon juice (to prevent mold growth), and
  • a few drops of food coloring, if desired. 
 I read on one of the recipes that using 3/4 cups of white glue would make it less sticky to work with, so I cut back on the white glue by just a bit after my first batch. Just mix all these ingredients together in a pan and stir with a wooden spoon until smooth. I also added a few drops of black food coloring so that the finished product would not come out white. That way if something chips or breaks the base color will be grey, which is less obvious. Some sites call for mixing this concoction over a low flame on the stove, which is what I did for my fist batch, but that requires you to stir it constantly and it takes about ten minutes to congeal. Also, clean up of the pan and spoon between batches was rough.
On subsequent batches, I followed another method I found that says you can cook it in the microwave. Just stir it all up, pop it in for 20 seconds, then stir again. Do this three times and it should be done. As I was experimenting with this process, I went a little more gently. I microwaved it for 15 seconds, then stirred, and repeated. It took seven sessions of 15 seconds each before it clumped up. Also, don't forget to switch to a microwave safe mixing bowl. I used a disposable food container. That way I could just toss it out when I was done. It did clean up much easier than the pan between batches.
After it starts to clump up, take it out of the bowl and knead it. It will be hot but not so hot you can't touch it. Some sites advocated using hand lotion on you hands and work space to keep the stuff from sticking too much. I found that dusting with corn starch was much more effective. I used a hardboard sheet covered with vinyl contact paper as my work surface. I dusted it liberally with corn starch, and kept my hands covered in corn starch as well. The whole process of kneading worked a lot like making bread dough. If the stuff was too sticky, just add a sprinkle of corn starch. If it got too dry, coat it with a little mineral oil. While I was working with it, I kept it in a zipper bag with a few drops of mineral oil to keep it from drying out.
For thick pieces of the stuff, it does take two to three days to air dry. I definitely recommend using an armature. I used aluminum foil as an armature. There is also a bit of shrinkage, maybe 20%. Also, very thin pieces are fragile. This stuff it a bit brittle when dry. Otherwise, this stuff is pretty cool to work with, and you can't beat the price. Anyway, this post is just a primer for my upcoming series of posts on the construction of the Cultists of R'lyeh board. See you soon.

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