Caulk a Bathtub

Water will penetrate your bathroom walls and cause expensive damage to your valuable home unless you take precautions with your bathtub.

Steps

 * 1) Examine the joint between the bathtub and the wall. Clean all old caulk, mildew and soap scum from the edge of bathtub. Be careful not to scratch surface of tub. Wipe with denatured alcohol to clean and remove any moisture from each seam.  Rubbing alcohol contains oil that leaves residue (to keep from drying out your skin) and should not be used for cleaning.
 * 2) Use caulk approved for bathroom surfaces. There are choices in color and price. It seems more silicone costs more. Silicone caulk for kitchen and bath has a mildew preventer built in it.
 * 3)  Apply masking tape to both sides of where you want your new caulk bead, with the edges of the tape lining up to exactly where you want the bead of caulk to stop.  This is a technique that professionals use to ensure a perfectly even-looking bead with no mess.  There should be about an eighth of an inch between the two pieces of tape.
 * 4) Load caulk tube in caulk gun. Using a sharp knife, cut the application tip on score mark. Opening should not be so big that a bead cannot be formed. Opening should not be so small that caulk tube seems highly pressurized. Most tubes have a thin barrier inside the tube to prevent the caulk from curing. Pierce the barrier by inserting a wire, nail or pointed object inside tip.
 * 5) Hold caulk gun over trash and depress trigger to move caulk forward filling the tip. Caulk should flow out, not squirt or drip. Release trigger lock to relieve the light pressure inside tube.
 * 6) Point tip in position at seam. Tip should be slightly above surface, nearly touching. As you begin to press trigger, watch flow of caulk. With one steady motion, move caulk gun straight along seam, creating a uniform bead. Before flow stops, quickly release trigger and begin to press again as you continue to create a uniform bead the entire length of seam. Do not stop until you reach corner.
 * 7) Repeat for each seam, usually three walls.
 * 8) When you stop, remember to release the trigger lock to relieve pressure inside tube or caulk will continue to flow out.
 * 9)  Smooth the caulk out between the pieces of masking tape, pressing it into the corner with your finger as you go along, and removing excess caulk.  Keep a few paper towels at hand to wipe your finger off if you need to.
 * 10)  Remove the masking tape before the caulk starts to skin over.  The bead should look neat and even, but you may need to clean it up slightly with your finger again for a perfect finish.
 * 11) Caulk must cure for 24/36 hours before exposing to water and moisture.

Tips

 * Fill the tub three quarters of the way full of water to allow the tub to sag while the silicon dries for 24 hours. Otherwise the tub will sag when you get in and pull on the seam causing possible long-term cracking and breaching.
 * A sharpened flathead screwdriver works quite well for removing old caulking (be sure not to damage underlying surfaces).
 * The process is very similar to decorating a cake.
 * Bead must fill seam between wall and bathtub. Bead must contact wall and tub uniformly along entire length or leaks will occur.
 * If you do not use the entire tube of caulk, you may plug the tip with an object such as a small wooden rod or nail and cover with plastic or tape. Caulk will keep for a short time.
 * You can smooth out the caulk with a wet finger, plastic spoon or rounded ice cube.
 * Use a small paper cup filled halfway with lukewarm water, add 2 to 3 drops dishwashing soap and stir gently with your finger to disolve. You don't want suds. Using this to wet your finger will make cleanup easier and the silicone will not want to stick to your finger.
 * Silicon caulk is very very sticky and will not come off your fingers easily. Therefore, wear latex gloves when applying silicone caulk
 * Clean up and smoothing is easily accomplished with paper towels and "Formula 409" or other similar household cleaner.
 * After removing the tape, smooth the edges that were next to the tape, ensuring that they are feathered to the surface. Otherwise, the edge will gather dirt.
 * When smoothing the caulk, start in a corner and go 1/2 to 3/4 across. Then start in the opposite corner and meet in the middle.  When meeting the already smoothed section, lightly lift your smoothing device so there isn't a hump.
 * Do one wall at a time because silicone films over rather quickly.
 * A little off topic, but when you have a tiled inside corner always use caulk instead of grout. Grout will crack out and will leak in the corners, whereas caulk stays flexible when it is cured. If you have large, sanded grout joints, you can usually find colored, sanded caulk in the same custom colors as the grout, although this isn't always the best choice for tub surrounds and showers.  For this application make sure you use caulk with some amount of silicone in it, or pure silicone.
 * To remove silicone from hands just rub them with a plastic bag. It makes cleanup instant and lets you use your fingers to smooth and finish caulking without worrying about stickiness.
 * Be sure to remove all traces of caulk & mildew before applying new caulk- -yes even that residue that seems like it will not come off.

Warnings

 * Exercise caution with knife and pointed objects.
 * Do not use bathtub until caulk cures. See tube for specific instructions.
 * Important Tip - Tub should be filled 3/4 full of water during caulking, this prevents any break in the seal due to increased tub weight when it is filled with water.

Related Tips and Steps

 * How to Remove Silicone Caulk from Hands
 * How to Clean the Tub
 * How to Maintain Your Spa or Hot Tub
 * How to Unclog a Bathroom Sink That Drains Slowly
 * How to Replace a Kitchen or Bathroom Faucet