What kind are you using. I have some DAS that works pretty decent. It depends on how thick the clay is. I was doing some mosaic floor tiles and made an 8"x8" section that was about 1/8" thick. Took 3 days to dry while sitting on my desk. That could be your problem. Sealing the outside might make it worse as I imagine it would prevent the moisture from escaping. I have heard of putting it in an oven to speed it up. But since ive never tried the oven techinque i dont have any temps or times to give you. Hope that helps anyways.
MrJuice
http://spaces.msn.com/tabletopgames
MrJuice
http://spaces.msn.com/tabletopgames
