Brian Ross
rossoon@imag.net
I think everything I have been using is on the D scale. My "90" hardness stuff is like a hockey puck - which is probably why I get good detail on my brooches.
I am not endorsing these sites; just happened to find useful explanations in them.
www.microphotonics.com/durometer.html
www.qualitest-inc.com/durometer.htm
Brian