Bathtub caulking or any caulking for that matter is about the most instantaneous reward you can get from a home repair project. It’s not important whether you are installing a new tub or re-caulking an old one, the procedure is pretty much the same except for the preparation effort needed.
To prep a new tub, you just have to install it and the tub wall that will surround it. To prep an old tub, you have to get all of the old caulk off first. Then scrub the area good to remove as much residue as possible. Always make sure the surfaces to receive the caulk are clean of dust and debris and dry. If you use alcohol after you’ve scraped most of the old caulk away, this will help dissolve the residue and dries quickly.
Your tub is now ready to receive the fresh caulk. Consult with your supplier for the best type of caulk to use for your climate. If mold and mildew are big problems, you will want to get the kind that costs a little more but is resistant to these banes of the bathroom.
An inexpensive caulking gun will be good enough for this job. If you already have one, it will be fine as long as the tube of new caulk will fit into the gun. After the tube is loaded into the gun, snip the end of the tube on a bias to the desired size of the bead of caulk. I like to cut a small notch in the long side of the tube to shape the bead as it is dispensed. You can always just spread it with a moistened finger if your technique isn’t too polished.
Pick an easy place to start. I recommend standing in the tub to make it easier to follow the circuit around the lip. Snug the plunger up to the end of the caulk tube and rotate the handle to engage the trigger mechanism. This will allow you to pump the caulk out at an even rate by pulling back on the trigger. Using your non-dominant hand, hold the caulk gun up to the lip to receive the caulk. Use your dominant hand to depress the trigger. By using your stronger hand, it will help reduce shaking and gaps.
Dispense the caulk slowly and evenly around the tub. If there are small places where the crack is too wide, just back up and fill in. With a small amount of skill, you may not have to go back and smooth up your work. If a nice round bead has filled all of the gap around the tub, you are finished. You will have about 10-15 minutes to use your moistened fingers to clean up a messy job. Using a wet paper towel, you can clean up any spills or bobbles with relative ease.
You can admire your work for now, but don’t let water touch it for a few hours. Sitting overnight or from morning until evening would be ideal.