Although the term “sealant” implies superior performance, the terms “caulk” and “sealant” are used more or less interchangeably throughout The Ins and Out of Caulking. These terms are also used interchangeably often in the building industry, even though there is a rational basis for distinction between the terms.
Modern caulks incorporate synthetic polymers. Higher performance caulks marketed for residential construction incorporate one of four different types of synthetic polymer: silicone, polyurethane, emulsified (latex) acrylic, or solvent-borne block copolymer. Of these, latex acrylic, silicone, and polyurethane caulks are widely used. Block copolymer caulks are relatively uncommon; they are specialty caulks, usually selected for their clarity, where this attribute is important. Each of the polymer types has its own particular (and in some cases, peculiar) advantages and disadvantages.
Latex acrylic caulks usually shrink during extended cure. Uncured latex acrylic sealant can, however, generally be applied successfully to cured sealant of the same type. A wide variety of emulsified resin (“latex”) caulk is available, and these products are in many ways the easiest of the sealants to use. In residential building, where the knowledge and skill of applicators are not particularly well developed, latex acrylic sealants may provide performance as effectively as silicone or polyurethane sealants even though they do not match the performance of these (usually higher cost) sealants in controlled laboratory testing.