Dingy, cracked or mildewed bathtub or shower caulk can make even a sparkling clean bathroom look dirty. You can correct this in 4 easy steps.
1 Using a stiff putty knife and a small, inexpensive razor scraper, remove all old material around the tub.
Dig out as much old stuff as possible so that a shallow groove is formed along the entire edge between the bathtub and the tile or the tub or shower surround.
2 Thoroughly scrub the entire area with a bleach-based cleaner and a stiff brush.
Rinse well, and allow to dry completely. A fan temporarily directed at the area will speed the drying process.
3 Using a latex-based tub-and-tile product, in either a squeeze tube or a caulking gun, fill the shallow groove with a thin, continuous bead.
While the line is still fresh and before a skin starts to set and harden - within a few minutes, at most - moisten your fingertip and use it to smooth it out and push it thoroughly into any gaps.
4 Carefully wipe away any excess with a damp cloth.
The trick is to use the least amount necessary to fill the small gap between two different materials and surfaces.
It should be nearly invisible when complete, and not protrude any farther than the tile or the edge of the tub or shower.
Otherwise, it can act as a trap for moisture and allow mildew to grow. Let it set for as long as the package directions indicate (it's usually overnight).
Finally, you can probably avoid ever having to do this job again by regularly drying tub surfaces, shower walls, fixtures, and nearby areas with a clean towel.
If stains do appear, try cleaning with a mildew-killer or other commercially available grout cleaner.
Ready to get started? Here are a few products you might need:
