Suppliers

For anything rubber or plastic, one of my favorite suppliers is http://smooth-on.com

For my plaster molds, my favorite parting compound, I get from http://perma-flex.com
I've used their polyurethane parting compound for years. The secret is to apply with a soft paint brush, use a hair dryer to dry, while dabbing at puddles with a dry soft brush. I use a very soft, 2" paint brush. Using this method, you only have to apply one coat. You will be left with a fine film of something that feels like wax. I use a thin coat for every mold I pour off the master block.