Best caulk for re-sealing tubs, showers and sinks

How to choose

Use silicone for wet joints and latex for painted ones

Use silicone where water runs, such as the joint between tub and wall. Tile detailing calls for a sealant joint at every change in plane, so the movement rating matters there.⁵ Red Devil, which sells both types, also points buyers to silicone around sinks and tubs.¹¹

Not everyone agrees. This Old House recommends a mildew-resistant acrylic latex for bathrooms because it's easier to replace, though latex shrinks more, dries harder and may need replacing sooner.¹² We found no measured comparison that settles it, but the published specs favor silicone.

Look for neutral cure and a stated class

A label that says 100% silicone doesn't mean nothing else is inside. Gorilla's safety sheets list 7 to 13 percent petroleum distillates, and the sheet for clear GE Supreme lists 1 to 5 percent hydrocarbon fluid.^{7 10} Nobody has measured what that does to a bead's life, so read the data sheet, but don't take it as proof of early failure.

Don't pay for a mold claim alone

A mold claim protects the sealant, not your wall. EPA's rule for treated products covers claims that protect the product itself.¹³ GE says soap and other residue can cause mold on surfaces, and Gorilla says cured sealant must be cleaned regularly to stop growth on top of it.^{1 2}

EPA calls moisture control the key to controlling mold, and says more ventilation and more frequent cleaning usually limit growth in damp bathroom spots.¹⁴ Run the fan or open a window during showers. Replace a bead that's black inside. One forum poster calls digging it out the longest-term fix and says bleach helps only for a while.¹⁵

Give it a full day before water

Read the footnote on any fast-cure claim. GE's 30 minutes applies only to a bead no wider than 3/16 inch, at 65°F or warmer and at least 50 percent humidity. Otherwise keep water off for 8 hours, and don't touch or clean the bead for 24 hours.¹ If you can spare a day, waiting 24 hours satisfies all three makers.^{1 2 3}

Spend your effort on prep

Every maker sheet wants old sealant gone and the surface clean and dry. Silicone won't stick over old silicone or soap residue, and GE says nothing dissolves it, so you have to cut and scrape the old bead off.^{1 8 12} Use plastic blades on plastic tubs and keep the blade low.¹² In two forum threads, poor prep was the most common explanation for peeling.^{8 9}

On a plastic or fiberglass tub, try filling the tub before caulking and leaving the water in for at least 24 hours, so the bead cures with the tub sitting low. Nobody has measured the effect, and one forum poster's bead peeled anyway, but it costs little.^{9 16}

How much to buy

One 10-ounce cartridge is plenty for a tub, since GE lists about 51 feet of 3/16-inch bead.¹ Squeeze tubes suit small repairs, and cartridges need a caulk gun.⁶