Clean Surfaces – Making sure that the surface you are going to caulk is clean and well-prepared is essential to achieving good adhesion and a smooth bead.
- Clean off any dust or dirt particles with water.
- Do not use soap.
- Remove any remnants of old caulking. New caulk will not adhere well to acrylic caulk that has been cured and will not stick at all to cured silicone caulk.
After you have removed most of the old caulk with a blade (being careful not to scratch the surface), you can apply a concentrated mildew killer. Finally, swab the joint with rubbing alcohol to remove soap scum, body oils, and other residue. Rubbing alcohol dries quickly and leaves the surfaces impeccably clean so the new caulking will adhere well.
Just another expert idea from Guy Calor, the Caulk King and CaulkWarmer!