Caulking compound, often called “tub-and-tile caulk” seals the crack between a wall—often covered with ceramic tile—and fixtures such as sink bowls and bathtubs. New tub-and-tile caulk is flexible, so it can handle the movement between the fixture and the wall caused by weight changes (a bathtub filling with water, for example) and expansion and contraction that heat changes cause.
Old caulk may become brittle and lose that needed elasticity. In addition, it can discolor with stains, or peel away from the surface.
If the caulk becomes brittle, it cracks and ceases to seal the gap between wall and fixture. Then water can drain down behind the fixture, into the wall, where it can cause mold and damage. So it’s a good idea to renew caulking annually.
Fortunately, anybody who can spread toothpaste on a toothbrush can caulk.
1 Remove the old caulk. Using a utility knife, cut the seal and pull away all the old caulk from the joint around the sink, bathtub, or countertop. Clean out the crevice to make sure the new caulking compound will adhere.
2 Apply a smooth, even bead of high-quality silicone tub-and-tile caulk to the crevice. Holding the caulking tube at an angle, draw it along the crack, applying a single bead about the size of a pencil (avoid doubling back over the bead). Be sure to completely fill the crack.
3 Smooth out the bead with your finger, and then carefully wipe off the excess with a damp paper towel or a damp rag (a paper towel is less messy because you can just discard it when you’re done). Allow the caulk to set before getting the area wet.