TheTradesmanShopHow to Recaulk a Bathtub So It Actually Lasts
Most recaulk jobs fail within a year, and it is always the prep, not the caulk. The tube is not the skill. What is under it and how dry it is decides everything. Do it this way and it will hold for years.
1. Why your old caulk failed
Caulk fails for three reasons: it was smeared over old caulk, it went on wet, or it was the wrong caulk. Latex caulk in a tub is a slow-motion failure; tubs flex and stay wet, and latex cannot handle either for long. If your old bead is peeling, black with mold, or cracked, all three sins were probably committed.
2. Get every bit of the old caulk out
All of it. Every speck. New caulk will not bond to old caulk; it bonds to the tub and the tile. Run a utility knife along both edges of the old bead, pull it out in strips, then use a caulk removal tool or a plastic scraper for what is left. Wipe the joint with rubbing alcohol to pull off the last film and soap scum. If you can see or feel any old caulk, you are not done.
3. Bone dry or do not bother
This is the rule that decides the job. Moisture kills the bond. After removal, let the joint dry completely, then wipe it with rubbing alcohol and let that flash off too. If the tub was used that morning, wait. Point a fan at it. Caulk stuck to a damp joint looks fine for a month and then lets go all at once.
4. Cut the tip small
Cut the nozzle at a 45-degree angle and start small. You can always cut it bigger; you cannot cut it smaller. The bead should just fill the joint with a little extra to tool. A fat bead looks amateur and takes forever to cure. Pros use small beads. Be a pro.
5. One bead, one pass, smooth once
Run one continuous bead down the joint in a single pass. Then smooth it once, with a wet finger or a caulk tool, in one steady motion. Here is where everyone ruins it: they keep touching it, pushing it around, trying to make it perfect. Every extra touch makes it worse. Lay it, smooth it, walk away.
6. Let it cure 24 hours
No water, no touching, no shower for a full day. Silicone skins over fast but cures slow, and water before it cures ruins the bond from the inside. Tape a note to the shower handle if you have to. Twenty-four hours of patience buys you years of seal.
Quick answers
Should I use silicone or latex caulk around a bathtub?
One hundred percent silicone, every time. Tubs flex when you step in and they stay wet; silicone flexes with the movement and shrugs off water and mold far better than latex. Use a kitchen-and-bath silicone with mold resistance. Latex is for trim, not tubs.
Why does my tub caulk keep getting moldy?
Constant moisture plus soap residue feeds mold, and poor ventilation makes it worse. Run the bath fan during and after every shower, squeegee the walls, and wipe the caulk line dry when you can. A mold-resistant silicone helps, but airflow is the real fix.
Can I just caulk over the old caulk?
No. New caulk bonds to clean surfaces, not to old caulk, so a bead over old material peels off in sheets, sometimes within weeks. It also looks lumpy and terrible. Strip it all and start bare. There is no shortcut here.