[QUOTE="Lozzo"] Grimly Curmudgeon says... I thought it was Nitrile. I made some exhaust gaskets for an RD400 from that stuff once, I told a mate and he warned me of the dangers of the stuff after it had burned before I handled them again, bearing in mind they'd been subjected to cylinder gases I was quite lucky. [/QUOTE] That's the stuff I was thinking about. Apparently, you need to cut the affected flesh off to get rid of it.