In terms of choosing eco-friendly alternatives to harsh chemicals, vinegar is the clear champion. Vinegar is biodegradable, can be kept on the shelf indefinitely, and won't leave toxic chemical smells or residues in your home. Vinegar makes an excellent cleaning product and can even tackle tough projects such as old or residual caulk. The acid in vinegar helps break down hard, sticky or old caulk and dissolves it so it can be effectively scrubbed away.
Pour two or three cups of white vinegar into the bowl and put on the latex gloves to protect your hands from irritation.
Dip the dish scrubber into the vinegar and then apply directly to the caulk. Hold the dish scrubber to the caulk for a minute to allow the vinegar time to begin dissolving the caulk.
Scrub the caulk energetically with the vinegar-filled dish scrubber. Dip the scrubber back into the vinegar mix as necessary.
Start with an edge of the strip of caulk, if possible. As you begin to dissolve the caulk with the vinegar, start pulling up the edge of the caulk with your fingers to speed the process.
Dampen the dishrag with warm water and wipe away any of the caulk residue that remains. If needed, repeat Steps 2 and 3 until all caulk is removed.