Caulking is done to seal gaps and crevices, and removing aging, mildew-infected caulking can be accomplished safely with some common painter's tools and all-natural products. Depending on the type of caulking used and the extent of the weathering, some jobs are easier than others. If you have a situation where the caulking is stubbornly sticking to the surface and won't simply peel off, there are a few non-toxic chemicals you can call into action to complete the task.

...
Old caulking can be unsightly, but safe removal is possible with some non-toxic home remedies.

Painter's Tools

A painter's 5-in-one knife is fitted with a pointed edge that is perfect for scoring strips of caulking and scraping the bead away from a surface. A retractable razor knife can also be used in areas where the 5-in-one knife doesn't work. These tools may damage underlying surfaces in sensitive areas, so either be gentle in those situations or use other softening methods before employing these particular tools. A plastic or hard rubber putty knife might also do the trick. For areas where you don't want to damage the surface around or under the caulking at all, spray the caulking down with water while using the putty knife or wrap a small wet rag around the blade of the 5-in-one knife and avoid using the razor blade. For caulking that is easy to simply peel off once you detach an end of the bead, use a pair of needle-nosed pliers and pull the caulking away from the top of the bead to the bottom.

Heat Application

A hair drier on a high setting or a heat gun on a lower setting will help soften caulking that will not peel away easily. Heat the whole bead you are targeting with sweeping motions. Be carful not to target one particular area for too long to avoid doing any damage to surrounding or underlying surfaces. Using the putty knife or the 5-in-one tool should be much easier with the bead of caulking heated and softened.

Hot Water and Alcohol

Applying simple hot water to the caulking can be effective in removing water-based caulking. Use an old rag or sponge and saturate the targeted area for about three days. The removal process should be much easier once the moisture is locked into the bead. For an extra edge, isopropyl rubbing alcohol can be applied. This will help encourage the separation of the bead of caulking from the surface it is clinging to.

Silicone Caulking Removal

Silicone caulking is typically much tougher to remove than other types. To avoid using toxic chemical products, it's best to use a razor knife to cut away the caulking bead and remove the excess with a scraper or by hand. Anything else that clings to the surface can be cleaned off with an abrasive pad soaked with denatured alcohol or mineral spirits.