title about says it. don't have the coin in front of me. believe it's a nice 1850s quarter. anyway, there is an old caramel tape residue on the obverse. anyway to gently dissolve and remove it?
A long soak in Acetone might disolve the tape & adhesive. Don't scrub it. Soak it. Unfortunately, the toning on the coin will probably have some pattern from the tape. This toning pattern should not be removed by the Acetone soak.
Show us some photos if you can Acetone will probably work but recognize that all tape residues are not created equal. It would be nice to see photos of before & after your treatment of this coin. You might want to rinse with water & then alcohol which dries quickly without spots. FYI- At my work, we use an adhesive tape that has an Acrylic adhesive. The tape is used to protect metal substrates during our handling. Unfortunately, Acetone will not dissolve this Acrylic adhesive. It is really tough stuff. The only solvent that would work on this adhesive is known to cause cancer & other major health problems (like death). I don't use it & I won’t list it here for fear that some amateur might try it.
Since tape residues vary greatly, you should always follow the polarity ladder in order: water>acetone>xylene Of course, stop when you find the magic solvent.
On the topic of acrylic solvents, not to get too specific, but I might be a little reluctant to use chlorinated organics on reactive metals independent of any health risks.
