Silicone caulk is a very popular option for sealing in bathtubs and other bathroom fixtures. The caulk prevents water from leaking into the walls or out of the bathtub and onto the floor. The silicone is often laced with a moldicide that kills any mold that may try to grow along the caulk lines, which also is useful in bathrooms or kitchens.
Silicone caulk should be used on a surface that has been cleaned and dried. Silicone caulks are often used to patch existing caulk lines or replace old caulk. It is very important that the user remove all of the old caulk first, because the new silicone caulk will not bind properly to it.
Silicone caulk is typically used on fiberglass, where it has the best bonding and sealing properties. It tends to create a smooth line that is not as brittle or hard as other types of caulk, which can also help in removing it from fiberglass. When on other surfaces, silicone caulk is one of the most difficult caulks to remove because of its bonding properties. It can also be difficult to apply for those unskilled in caulking because of its runny nature.
There are two main types of silicone caulk. The first is a 100 percent silicone solution. Its base is made of silicone with no other compounds added, and it will typically take the longest to dry. The other type is a silicone hybrid that is made with a combination of silicone and latex to give the latex some of silicone's more flexible properties. This type tends to dry slightly faster.
Silicone does not naturally cure by drying. Instead, the silicone caulk has a curing agent. Once this agent is exposed to air, it undergoes a chemical reaction that dries and bonds the silicone. Typically, users caulking bathtubs or similar objects should wait overnight for the caulk to cure before using them.
Because silicone caulks depend on this curing agent, they have a shorter shelf life than other caulk products. An older silicone caulk may have a faded curing agent and not cure properly at all. If the caulk is around a year old or more, the user should create a test spot of the caulk and see if it cures. If it has not cured in 24 hours, the curing agent has gone bad and a different caulk should be used.