Contact adhesive is a remarkable substance that has the ability to adhere to itself, and bond anything it is attached to with it. That said, you don't want to inadvertently spill it on anything else or you will have a hard time removing it. Sounds simple enough, but unfortunately since contact adhesive is made from rubber, many of the removal products may eat away at your surface as well, so you have to be careful. Follow the advice below for the best methods to get this job done.
Step 1 - Detach Bonded Pieces if Needed
If you have somehow managed to get contact adhesive on two pieces of rubber, you will need to soften the adhesive in order to get them apart. Using a hairdryer works well for this. Apply steady heat on the glue until you can pry the two pieces apart. Now you can to try some of the following steps in order to remove the adhesive completely.
Step 2 - Start with Scraping
Now that you have a surface (or two) to work with, you need to try and scrape off as much of the built up adhesive as you can. You can use a small putty knife or paint scraper for this. Go slow and take your time; the more adhesive you remove with this step, the easier the rest will be. Also, take care not to puncture or damage your rubber surface.
Step 3 - Try Non-chemicals First
Non-chemical solutions are safe to use and safe for the environment, so it's always best to try them first. If the rubber surface is small enough, try soaking it in some vinegar for about 15 minutes. Place some in an empty spray bottle and saturate the adhesive spot to help break it up. Then, after you have let it soak, use a stiff-bristled brush to scrub at the spot. This should get the remainder of the glue off, but if it doesn't you can try step four.
Step 4 - Move to Chemicals
If your contact adhesive is extremely stubborn and the previous steps have not taken care of the problem, you need to bring in the chemicals. However, before using any of these, make sure you are in an area with proper ventilation and that you wear rubber gloves to protect your hands.
The first thing to try is Zippo lighter fluid; more than likely any lighter fluid would do, but Zippo seems to have the best reputation for this. Squirt a little on a rag, and it should remove the contact adhesive easily with a little rubbing.
If you don't have any lighter fluid handy, you can also use lacquer thinner to remove the adhesive. Large amounts of this will damage rubber, but you only need to use a small amount, not soak the rubber in it. Pour some of the thinner onto a rag and rub it onto the adhesive; it should come right off. You could also use some acetone for this, although it's recommended that you dilute the acetone first.
Step 5 - Clean up Residue
Make sure after the contact adhesive is removed that you do a quick clean of the rubber surface to make sure all traces of the chemicals are gone. A simple soap and water mixture should do the trick. Rinse thoroughly afterward and wipe it dry as well.