Oil sand
The basic recipe for K-BOND is:
100 lb. of very fine silica sand (100 to 150 GFN)
6 - 7 lb. of Bentone (cheapest you can find)
3 lb. of Indopol L-100 oil
0.10 to 0.20 lb. of Propylene Carbonate (or Methanol or Isopropanol)
http://www.artmetal.com/village/BBS/bbs_forum.cgi?forum=sculpture&read=000275-000273.msg