How to Caulk Around a Tub
Take aim at old, cruddy caulk, and give your tub a fresh new seal
You've seen the ominous signs of aging caulk. First it was the brown tinge along the edges. Now its smooth and supple skin has turned brittle and cracked, opening the way for stubborn colonies of mildew to take hold, or for water to seep through and turn wallboard and framing mushy. Whether it's around your sink, between a tub and its tile surround, or covering the joints of your shower stall - it has got to go.
Fortunately, caulk is cheap, and applying it isn't difficult. All you need is an hour, a few common tools, and materials easily found at any hardware store. But as easy as it is, you still have to do it right, or you'll be caulking again next year, says This Old House general contractor Tom Silva. "The key is to completely remove the old caulk, including the residue you can't see," he says. "You've got to start fresh with a clean, smooth, dry surface."
Follow Tom's steps on the next page, and "you should get five to ten years out of that seal, easy," he says.
The best caulks for tubs, sinks, or shower stalls come in tubes labeled “Tub and Tile” or “Kitchen and Bath.” These are either acrylic latex or silicone compounds that have been chemically tweaked to resist mildew and to stick to smooth, nonporous surfaces. But they have distinctly different personalities.
(A) Silicone: Tenacious, waterproof, and very flexible, this type of caulk is also finicky about surface conditions, difficult to smooth, requires mineral spirits for cleanup, and emits a nose-wrinkling odor until cured. It leaves a residue that's hard for anything - including new silicone - to stick to. That's why formerly siliconed surfaces should be scrubbed with an abrasive pad soaked in mineral spirits. Silicone caulk has a color palette limited to clear, white, and almond.
(B) Acrylic Latex: Compared with silicone, this kind of caulk is much more forgiving about the type and cleanliness of a surface it's applied to. Smoothing it is easy, it cleans up with water, and it doesn't have much if any smell. While it does shrink more and dry harder than silicone - and will probably need to be replaced a little sooner - the replacement job should go faster. Acrylic latex caulk comes in a rainbow assortment of colors to match sink and tub glazes.