The first time I caulked a bathtub, it looked like a kindergartner had squeezed an entire tube of toothpaste around the edges. Lumpy, uneven, smeared into the grout lines, and somehow on the ceiling. I have no idea how I got caulk on the ceiling.

My landlord came by a week later for an unrelated repair, looked at the tub, and said nothing. Just a very long pause. I redid it the next weekend and the second attempt took half the time and looked ten times better because I finally learned the one trick nobody tells you.

Remove All the Old Caulk Completely

New caulk will not stick to old caulk. It peels off in sheets within weeks. Cut out every trace of the old bead with a utility knife and a plastic scraper. Then wipe the joint with rubbing alcohol to remove soap scum and residue. The surface must be bone dry and absolutely clean — any moisture and the new caulk does not bond.

Use a hair dryer on the joint for a minute if you are in a hurry. Wait longer if you are not. Caulk over damp surfaces fails silently — it looks fine for a month, then mold creeps in from behind and you have to start over.

Cut the Nozzle at a 45-Degree Angle

And cut it small. The hole should be no bigger than an eighth of an inch. A smaller hole gives you more control and a cleaner bead. You can always cut it bigger, but you cannot uncut it. I learned that the expensive way with a tube of silicone that cost fourteen dollars.

The Tape Trick That Changes Everything

Apply painter’s tape on both sides of the joint — one strip on the tub, one on the wall — with about a quarter-inch gap between them. Run a smooth bead of caulk down the gap. Immediately wet your finger and run it along the bead in one continuous motion to press it into the joint and create a smooth concave surface.

Now here is the part nobody told me: pull the tape off immediately, while the caulk is still wet. Do not wait for it to dry — if the caulk skins over before you pull the tape, it tears ragged edges. Peel slowly at a sharp angle away from the bead. The result is a perfectly straight line that looks like a professional did it.

Leave the caulk to cure for twenty-four hours before using the shower. Water on uncured caulk ruins the seal.