Essentially bathtub caulk is used to keep water from leaking under or around the seams of your tub which, if allowed to remain, can really damage your floor and walls. If you find that your bathtub caulking is leaking then it is important that you have it replaced instead of ignoring it. If you think about it, the repairs necessary due to the water damage will far exceed the small cost and bother of taking care of it now before there is a problem. Bathtub caulk is an interesting substance as it is both a glue and a sealant so it is the perfect product for the job.
Before you begin applying, it is necessary to remove any old bathtub caulk. This can be achieved by using simple tools such as a putty knife or a screwdriver. Just make sure while doing this that you are careful not to accidently scratch your tub. Now you should clean off the area where you will be applying your bead of bathtub caulking. It is good to use a bathroom cleanser that is designed for removing soap scum.
You will quickly find out that there are several different products for caulking bathtub fixtures and they are made from different substances. The two most common types are those that are made from silicone and those made from acrylic latex. In general, it is best to choose the silicone products because it can act as a natural barrier against the formation of mold and mildew. The only downfall about choosing this one is that it can be very difficult to remove completely, so when it comes time for replacing it it will be a hassle. Just make sure that you do not use an exterior caulk even though it may seem like a better choice.
Now that you are finished with these preliminary steps you can go ahead and apply the bathtub caulking. One thing that some plumbers recommend is that you fill the tub with water first, the idea being that the weight will force the tub downwards so you can achieve a tighter seal. It can be difficult to apply a bead of caulk in a manner that gives it a professional look so it does take some practice. Just do your best to apply the bead in one smooth motion. You can even stick a couple pieces of masking tape to the beginning and end of the line to prevent you from getting caulk everywhere.
Once you have finished applying your line of bathtub caulk you should give it about a day before you use the tub again, just to make sure that you do not get it wet. If there are any spots that are not even then put on a pair of latex gloves and smooth them out with your finger.