Excellent low level look at what's involved in formulating 1 part silicone rubbers and enough information to, literally, make your own. http://www.gelest.com/Library/18One.pdf SR prices seem to be dropping and brands available increasing (in NZ at least) to the extent that it would be unrealistic for most people to consider 'rolling their own". But, knowing that you could, and an understanding of some of the underlying issues involved may make this worth looking at. Russell McMahon . -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist