Remove Old Caulk and Recaulk a Shower

Shower caulk fails. Water gets behind it, mold grows, the bead darkens, and the seal breaks down—usually somewhere between two and five years depending on ventilation and bathroom humidity. Replacing it is straightforward work, but it's where most people go wrong by rushing the prep. The difference between a caulk job that lasts five years and one that lasts five months is the time you spend removing the old material and getting the surface bone dry. New caulk doesn't stick to old caulk, and it won't cure properly against damp substrate. This job takes a morning and costs almost nothing. It's worth doing right.

1. Cut Out Old Caulk Fast. Use a caulk removal tool or a sharp utility knife held at a 45-degree angle to cut through the old caulk bead. Work along the entire joint—both the horizontal seam where the tub meets the wall and the vertical seams where walls meet. Make multiple passes if needed. Once the bead is cut, use a plastic putty knife or old credit card to pry and scrape the caulk away. Don't use a metal tool; it will gouge tile or acrylic surfaces. Pull the caulk out in strips if it comes cleanly.
2. Extract Every Last Bit. After the bulk is gone, you'll have hardened bits stuck in the joint. Use a plastic or wooden scraper to remove these. Work methodically along the entire seam. Some old caulk may be embedded in grout or against sealant—get as much as you can without damaging the substrate. Pay special attention to inside corners where old caulk tends to hide.
3. Dissolve Soap Scum and Mold. Fill a spray bottle with white vinegar. Spray the entire joint—tub-to-wall, wall-to-wall, everywhere you'll be caulking. Use an old toothbrush or small grout brush to scrub the seam vigorously. Vinegar dissolves soap scum, mold spores, and mineral deposits that will prevent new caulk from bonding. Let it sit for 10 minutes, then scrub again. Spray with clean water to rinse and let it dry.
4. Eliminate Every Drop. This step is non-negotiable. Even damp caulk will fail. Use compressed air from a spray can to blow out moisture from the joint, paying special attention to corners and crevices. If you have a hair dryer, run it on low heat along the seam for 5-10 minutes. Open bathroom windows or run the exhaust fan. Wait at least 30 minutes, preferably an hour, before moving to caulking. Touch the joint with your hand—it should feel completely dry and cool.
5. Frame Your Bead. Run painter's tape along both sides of the seam you're about to caulk, about 1/4 inch away from the joint line. This creates a guide for a neat bead and protects tile, grout, and acrylic from excess caulk. On the tub-to-wall seam, tape the tile above and the tub rim below. On vertical wall seams, tape both walls. Press the tape firmly so caulk doesn't seep underneath.
6. Load and Prime Gun. Insert the caulk cartridge into a half-barrel caulk gun, pointed upward. Depress the trigger a few times until caulk reaches the tip. Lay the gun on a newspaper and use a utility knife to cut the plastic nozzle at a 45-degree angle, about 1/8 inch from the tip. The size of this opening controls bead size—smaller opening for trim joints, larger for gaps. Start small; you can always make it bigger. Wipe the tip with a damp rag to remove any excess.
7. Run One Continuous Bead. Start at one end of the seam—a corner is usually easier. Hold the gun at a 45-degree angle with the nozzle tip just touching the joint. Squeeze the trigger steadily and move along the seam at a slow, constant speed. Don't stop and start; one continuous bead is stronger than multiple short sections. Let the caulk fill the gap; don't force it. Apply caulk to all horizontal seams first (tub-to-wall, bottom of wall seams), then verticals. Work in sections if the joint is long—15 to 20 feet at a time is manageable.
8. Smooth It Into Shape. While the caulk is still wet (within 5-10 minutes of application), use a caulk tooling tool or your index finger to smooth the bead flat into the joint. Wet your finger slightly with water or run it under the tap. Press it into the caulk bead at a slight angle and run it along the entire seam in one smooth motion. This removes excess caulk, creates a concave profile that sheds water, and bonds the caulk to both surfaces. Do this methodically—one pass per seam is usually enough.
9. Peel Tape at Low Angle. Peel the painter's tape away 10-15 minutes after tooling, while the caulk is still slightly tacky but firm enough to hold its shape. Pull the tape at a shallow angle (almost parallel to the surface) rather than straight back, which prevents the caulk bead from tearing. If the caulk has already hardened, you can still remove tape, but it won't give you as clean a line. If you pull tape too early, the wet caulk will drag and look messy.
10. Wait Full 24 Hours. Silicone caulk typically cures in 24 hours, but bathroom humidity can extend this. Close the bathroom door and windows if possible to avoid external moisture while it cures. Don't run the shower, take baths, or splash water near the freshly caulked seams for at least 24 hours. Check the cartridge label for the specific product's cure time—some premium caulks cure faster. After 24 hours, the caulk should be fully flexible and waterproof.