Most folks don’t shop for caulks and sealants like they do for bathroom fixtures, but considering the job that caulks are expected to do and their high visibility, it might not be a bad idea. The problem is, there are an awful lot of caulks and sealants on the market, so choosing among them is difficult. Caulks basically do two jobs in the bathroom: seal against moisture intrusion and provide a pleasing joint between fixtures and wall finish materials. For the most part, careful detailing will minimize the reliance upon caulk for both functions, but there are still instances when it is necessary.
Types of caulk
While there are about a dozen types of caulks available for residential use, caulks for use in bathrooms fall into three basic categories: latex, acrylic latex (sometimes with silicone), and silicone.
Latex caulks are easy to apply and easy to clean up because they’re water based and hold paint well. I like to use them when painting with latex paint because they are cheap and fill cracks and holes easily, and can be painted over almost immediately. However, they aren’t very water resistant or flexible, so they’re a poor choice for general-purpose applications in the bathroom.
Acrylic latex caulks are more flexible than regular latex and are usually available in a fungicide-treated version for bathroom use. The fungicide gradually leaches out of the caulk over the course of about 5 to 15 years, helping to prevent mildew growth for that period of time. These caulks are a bit more expensive than plain latex caulk, but they are paintable and work well as a general-purpose caulk, which makes them worth the extra money. There are also siliconized versions of acrylic latex caulks, but the percentage of silicone is so low (typically less than 2%) that …