Silicone caulk (acrylic silicone/acrylic sealant/silicone/sealant/adhesive/potting sealant/potting adhesive/potting compound/UV glue/flange sealant/conductive sealant/electrical sealant/electronic adhesive/epoxy sealant/epoxy adhesive) is the product of choice for damp bathrooms, as it keeps seams sealed to resist water. Unlike its water-soluble, latex caulk counterpart, silicone requires chemicals such as mineral spirits for cleanup. Installed the right way, silicone sticks to the surface, has minimal shrinkage and isn’t susceptible to mold or mildew underneath. Clear silicone can yellow over time, but it’s also available in white and other colors.
Water-resistance is the goal, so any seam near a water source is a good candidate for silicone. Common areas are between the top of the bathtub and tub surround, along seams in a prefabricated shower wall insert, around a shower stall door enclosure and between the bottom edge of a tub and the floor. Caulking around the vanity sink keeps water from seeping into the cabinet. Some flooring also requires silicone around the perimeter of the room, especially vinyl and laminates installed in bathrooms. Silicone is not just a sealant (acrylic silicone/acrylic sealant/silicone/sealant/adhesive/potting sealant/potting adhesive/potting compound/UV glue/flange sealant/conductive sealant/electrical sealant/electronic adhesive/epoxy sealant/epoxy adhesive) ; it’s an adhesive that bonds the vanity countertop with the top edge of the vanity cabinet.
Silicone needs a clean, dry surface with which to bond. Oils, even from fingerprints, interfere with adhesion. Dirt or other particles trapped under the silicone lead to loose spots after it cures; this creates spaces where water might seep in. Clean the area where you’ll caulk using a rag or paper towel and nonresidue cleaner, and wipe the surface dry. Rubbing alcohol also cleans and doesn’t require rinsing. Dried paint drips are another impurity that interferes with the bond, so scrape or otherwise clean off old drips and spatters before using silicone. It will stick to the paint, but paint may loosen and lift the silicone with it.
Caulk tubes have a sealed, plastic applicator tip, some of which are marked for cutting. A utility knife or the cutter on the side of a caulk gun cuts the tip at an angle or slant, which helps apply and distribute silicone in a neat bead. A bead is the line or stripe of product that’s produced when silicone is squeezed from the tube. The right diameter for the cut is approximately 1/16 inch, but a precise measurement and angle aren’t necessary. Opening the tip doesn’t always expose the silicone, as some tubes have a foil or plastic seal inside the applicator. A long nail, wire or the metal rod attached to the side of some caulk guns is thin enough to fit through the tip and pierce the seal.
Silicone is available in small tubes and larger caulking tubes. Small tubes resemble a tube of toothpaste, and larger ones have a plastic or cardboard sleeve that fits into a caulk gun. Unused product left inside the tube doesn’t store well and often dries, even if you’ve capped or otherwise sealed the cut tip. Use a small tube if the job is small, such as around the base of a toilet.
Applying silicone takes a bit of practice if you aren’t familiar with how to use it. The longer side of the slanted cut faces up, with the tip positioned equally on both sides of the seam. For example, when caulking between the top of a bathtub and the bottom row of tiles, position the tip equally on the edge of the tiles and tub. Squeezing the tube or caulk gun gently and pulling the tip evenly across the surface produces the neatest bead. For a smoothed surface, wet a fingertip and draw it across the silicone (acrylic silicone/acrylic sealant/silicone/sealant/adhesive/potting sealant/potting adhesive/potting compound/UV glue/flange sealant/conductive sealant/electrical sealant/electronic adhesive/epoxy sealant/epoxy adhesive) .