I'm a bit confused because you speak of "extracting the soft parts" and
"pulling the tissue out", and yet you say the shells are limpets?  Limpets
are usually just about the easiest shells to clean - even easier than
bivalves.  I can see where there might be a problem though if the shells are
thin and fragile, and the tissue is very hard and adherent.  Ethanol hardens
tissue primarily by dehydrating it, and the best way to soften the tissue is
by rehydrating it. Just soak them in water for a few hours to overnight and
the tissue should become softer.  It may not completely regain its original
texture because the alcohol may have permanently denatured some of the
proteins; but it should become considerably softer than it was in the
alcohol.  Don't leave them in water for days on end though, as decomposition
may begin to occur, which can release acids that may damage the shell.  If
you want to guard against this possibility, dissolve a spoonful of baking
soda (sodium bicarbonate) in the water.  This will immediately neutralize
any minute amount of acid which might be released.  If the tissue is still
strongly adherent to the shell after rehydration, you might loosen it by
freezing and thawing (not in water! - just the specimens themselves).  Try
it on a couple of specimens first, to make sure the fragile shells can
withstand this treatment without cracking.

Paul M.

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