heruursciences wrote:
The rubbery tarry stuff that is used in older hene tube heads
dissolves in dichloromethane (DCM) used in paint strippers, The
silicone stuff is pretty impervious to all but mechanical attack.

FWIW There is a home decorating product called 'silicone eater' designed
for removing sealant from hard surfaces by dissolving it a little.

http://www.cglass.co.uk/everbuild-everflex-silicone-eater-pr-17657.html

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Adrian C