Caulk, a Non-Porous and Flexible Material

Once the joint and adjacent surfaces are completely dry, new caulk can be applied. Caulk, in general, is a non-porous, flexible material that adheres to the surface of building materials along a joint. While there are many different types of caulk, you should use a specially formulated silicone caulk for fixtures and materials in a bathroom. Kitchen/bath silicone caulk is permanent, waterproof, flexible, shrink-proof, crack-proof, and resistant to mildew. It is available in a variety of colors or in a paintable formulation. It is sold at home improvement stores in tubes that are intended to be used with a caulk gun as well as hand-squeezable tubes or pressurized cans. Prior to applying caulk, ensure that the adjacent materials along the joint are fairly tight to one another, with less than 1/8" gap. If the gap is larger than 1/8", a foam backer rod should be pressed into the gap to fill the void. While it's not entirely necessary, masking tape provides beginners with a professional appearance, ensuring a clean and straight bead. Apply masking tape to both surfaces adjacent to the joint, about 1/8" away from the joint. After the joints are taped, you should prepare the tube of caulk. Using a utility knife, cut at a 45-degree angle to remove the tip of the caulk tube at the 1/8" bead score mark. Any less and you won't have a bead to work with; any more and you'll have too much. I prefer to use just the right amount, if not less, and then come back to hit an area again if necessary. Once the tube is open, place it in the caulk gun. Have plenty of paper towels and/or rags available, along with a small pail of water. When you have finished applying the caulk you can use a wet finger or caulk applicator to smooth the bead. Immediately remove the masking tape, pulling it away from the bead of caulk on a 45-degree angle. Allow the new joint time to set up: some kitchen/bath silicone caulks set up in 1–3 hours. While this may be the case, I prefer to wait 24 hours before taking a shower or bath. Source: buildipedia.com