Correct me if I am wrong, since my days of college industrial work are way in the past, but I seem to remember bagged powdered additives in the sand to help the cavity to hold its shape.
Yep. Foundry sand, when ready to use, is pretty sticky. Larry Jackman was right in saying that it is moistened to make a mold, but don't think it's just dry sand with some water. As they say on TV, don't try it that way at home.
Anthony Thompson Dept. of Materials Science & Engineering University of California, Berkeley thompsonmarytony@...
