Caulk comes in many types (latex, silicone, and urethane) and choosing the right caulk for the job is important. Using the right caulk will both seal and protect, whether it’s gaps around a window or a tub — and you won't have to repeat the job any time soon.
Silicone is a great overall caulk and essential if you’re working with nonporous areas, such as bathtubs, showers, sinks, and so on.
Tub and tile caulk is an acrylic sealant that includes a mildew-resistant ingredient that makes it ideal in wet areas.
Urethane is also a good caulk for most other surfaces and has the added bonus of being paintable.
Elastomeric latex caulks are great for exterior cracks because it prevents the seal from expanding and contracting.
Caulk is available in 10-ounce tubes that fit into a caulk gun. A 10-ounce tube is enough to caulk around the average door or window. The gun has a trigger handle that you squeeze, which forces the caulk out the nozzle to form a bead. You can also buy caulk in 5.5-ounce squeezable tubes that don't require a caulking gun. Caulk and caulk guns are available at most home stores and hardware stores.
When opening a new tube of caulk, cut just a small piece off of the nozzle tip. Insert a piece of wire or a nail to open the seal, and then test the size of the bead. Remember, you can always cut the tip shorter for a bigger bead.