masking tape is a pressure sensitive adhesive on a paper carrier. this masking tape was old enough that the carrier lifted off easily, but the adhesive had hardened to the paper. to remove it, acetone is used. we began with an acetone chamber (acetone soaked blotters) but we could tell it was too aggressive. it softened the adhesive so it could be removed, but it also began to soak through the paper. we switched to removing it with an acetone soaked cotton swab, and were successful.
acetone soaked blotter, making a solvent chamber
adhesive starts to soften
removal of adhesive using a cotton swab!
(sometimes soaked with additional acetone)