Recaulk a Bathtub

Caulk fails. Water gets behind it, mildew creeps in, and what started as a thin protective seal becomes a black-edged liability. Most people notice it's bad six months after it's bad, which means the grout behind it has been taking on water for half a year. Recaulking a tub is one of those tasks that separates careful homeowners from the ones who let small problems become big ones. The work itself is straightforward, but doing it right requires patience in two places most people rush: removing every trace of old caulk, and not touching the fresh bead once it's laid. Miss the first and the new caulk won't stick. Rush the second and you'll smear what should have been a clean line. Done well, a recaulk job lasts five to seven years and keeps water exactly where it belongs.

1. Strip it to bare joint. Use a utility knife or caulk removal tool to cut and peel away every bit of old caulk from the joint. Work the blade under the edge and pull up in strips. Get into the corners where caulk hides behind itself. This step determines everything that follows.
2. Kill residue and oils. Scrub the entire joint with rubbing alcohol on a clean rag to remove soap scum, oils, and any caulk residue. Pay attention to the vertical corner where the wall meets the tub. Let the alcohol evaporate completely before moving on.
3. Moisture is the enemy. Let the joint air dry for at least two hours, or use a hair dryer to speed the process. The surface must be bone dry. Any moisture will prevent the new caulk from adhering properly and lead to early failure.
4. Frame your target. Apply painter's tape along both sides of the joint, leaving a gap that matches your desired caulk width — typically a quarter inch. Keep the tape lines parallel and smooth. This gives you clean edges and catches any excess.
5. Size your opening right. Cut the tube tip at a 45-degree angle, making the opening about the diameter of the joint you're filling. Puncture the inner seal with a long nail or the built-in poker on your caulk gun. Load the tube and test the flow on cardboard.
6. One pull, one bead. Hold the gun at a 45-degree angle and pull it smoothly along the joint in one continuous motion. Keep steady pressure on the trigger. Don't stop mid-seam. Work at a pace that lays down a consistent bead without gaps or lumps.
7. Smooth while it's hot. Wet your finger or a caulk tool and smooth the bead in one pass, pressing it into the joint. Work quickly — silicone starts to skin over within minutes. Remove the tape while the caulk is still wet, pulling at a low angle away from the bead.
8. Patience pays off. Leave the caulk untouched for 24 hours before exposing it to water. Don't test it, don't touch it, don't run the shower. Silicone needs time to fully cure and bond to the surface. After 24 hours, it's ready for normal use.