Old masking tape discolours and becomes ragged and brittle. Trying to simply tear it off is often not successful. Bits and pieces of the tape will tend to cling, making the area look ugly and ragged. The method to remove the remainder is similar for all surfaces, whether the tape is stuck to wood, metal, plastic or fabric.
Turn on a hair dryer and hold it 3 to 4 inches from the tape to blow hot air. The heat may loosen the old masking tape, making it less brittle. This may make it easier to remove in one larger piece, rather than in several slivers.
Turn off the hair dryer and use a scraper to try to scrape up one corner of the tape. If you are successful, gently pull the tape up and back to remove as much as possible.
Dampen a sponge in warm water. Add a drop of dish soap to the sponge. Rub this over the remaining masking tape, saturating it. Let it just sit for a few minutes -- the soap will help loosen the adhesive.
Use a plastic scraper or similar item to gently scrape a corner of the tape. Once you’ve got a corner lifted off the item, slowly pull the tape with your fingers.
Re-apply the soapy sponge if necessary. If the tape proves very difficult to remove with this method, then dry the area with a towel and apply WD-40.
Use the scraper to remove the remaining bits of masking tape. Wash the area again with the sponge, if you used WD-40. Rinse the surface with a damp cloth and then dry with a towel.
This method is suitable for all surfaces except cardboard or other surfaces that should not be wet. In these cases, use only WD-40 and apply it to the tape only. Scrape off the tape then remove excess WD-40 with a dry cloth.