Cured silicone is a notoriously difficult substance to remove from any surface. To get it off, you often have to resort to scraping and pulling, and the procedure can be painstaking. While you can find industrial silicone remover products, they're not safe for home use. Instead, you can use a number of safer options, some of which you may already have.
Silicone Caulk Removal
Silicone caulk lasts for many years, but it does wear out, and when it does, you need to remove it before you can apply fresh caulk. Anyone who has ever done this knows that some household solvents soften silicone caulk, but none dissolves it. A common removal strategy is to soften the caulk with a generous amount of a softening agent and then cut it off with a knife or pull it off with pliers. After the bulk is gone, you typically use the same solvent in combination with a scouring pad to clean up the residue.
One item you may have on hand that helps soften silicone is mineral spirits, which is suitable to get silicone off of hard surfaces like tile, marble or concrete. For removing it from plastic or painted surfaces, however, you should use isopropyl alcohol, which won't harm the surface. Regular alcohol you may have for home use may not be strong enough to do the job. Instead, try an industrial-grade isopropyl alcohol with 99 percent purity.
Other silicone solvent options include toluene and xylene. Always consider the material you're cleaning when choosing a solvent to make sure they're compatible. Test the solvent you choose on a hidden spot before you use it on a larger scale to make sure it doesn't cause any damage. It's also important to read the product instructions, follow all instructions and warnings, and allow for proper ventilation.
Silicone caulk has an odor that resembles vinegar because, like vinegar, it contains acetic acid. Consequently, white vinegar is another solvent you can use to soften it. It may not work as well as mineral spirits or alcohol, but it poses little danger to the substrate to which the caulk adheres. Rubbing a tabletop exposed to silicone wax with vinegar may safely remove some of the silicone.
Cutting Out the Bulk
Solvents such as vinegar or mineral spirits, and even stronger ones like lacquer thinner, swell cured silicone caulk. This loosens its adhesion to the substrate and makes the caulk easier to cut with a knife.
To remove stubborn caulk, you can either apply the solvent repeatedly or soak a rag and place the rag on the caulk. Once it softens, cutting as closely to the substrate as possible with a sharp knife while you pull the bead is the most efficient way to remove the bulk. Once that's gone, a thin residue usually remains behind.
The residue that remains after you've cut out the bulk of a bead of caulk can still prevent new caulk from adhering and must be removed. Rubbing it with sandpaper or an abrasive pad isn't a good strategy because the caulk tends to form small balls that stick to each other and to the paper or pad. The best strategy is to soak the residue with more mineral spirits, alcohol or vinegar to further soften it and then scrape it with a pull scraper or sharp knife. Continue working on the residue using this strategy until it's removed completely.