Acetone (fingernail polish remover) is a good general solvent, but like any
solvent, there are some things it won't dissolve.  It dissolves some
plastics and waxes, but others will not dissolve in it.  It mixes with some
oils, but not very well with mineral oil.  Like alcohol, it mixes readily
with both water and hydrocarbons (even though water and hydrocarbons won't
mix with each other).  There is some disagreement about whether acetone is
safe to use on shells.  It will not attack the actual substance of the
shell, however it has an very strong affinity for water and will literally
suck the water molecules out of anything you put in it (including your
skin).  Some collectors feel that this has an adverse effect on some shells,
especially pearly and highly glossy ones.  I have not used it on shells, so
I don't know.  Acetone is extremely flammable (about the same as gasoline)
and volatile, can be absorbed through your skin, and the vapors are harmful
to breathe.  There is no great danger in using a little bottle of nail
polish remover, but a bucket of acetone is very hazardous, and a good thing
to stay away from.  Most materials that can be dissolved in acetone can also
be dissolved in safer solvents.  One exception is lacquers - which is why
such a potentially hazardous chemical is still sold as fingernail polish
remover.
Paul M.