As ever, I am in awe of your greens stuff skills.
To be honest B, the skull was looking bloody awful just 2 minutes before this pic was shot. I had moved the GS around so much with my metal tools it was distorted and not very skull-like. I let it cure a bit, took the rubber sculpting tools to it and everything came good very quickly.One lesson I never seem to learn is using too much GS. However, the skull in the pic uses a tiny amount, so isn't 2" thick when finished.