calks

Calks are wedge-shaped pieces of material inserted into joints to create a watertight seal, primarily in traditional woodworking and shipbuilding. The term is an older spelling of caulk, and calks is a variant form that appears in historical texts. In many contexts, calk and caulk are used interchangeably, with calk often referring specifically to the material or the act of sealing.

Historically, calks were driven into the seams between wooden planks or boards to fill gaps and prevent leaks. In shipbuilding and timber framing, oakum (tarred fibers) and pitch or other sealants were used as the filling material, and caulking irons and mallets were employed to compress and seat the calks into place. The process of sealing joints by this method is called caulking.

In modern practice, the term remains in use mainly in restoration, traditional boatbuilding, and woodworking contexts. Contemporary sealants—such as polyurethane, silicone, and mastics—often replace loose calks, especially in new construction. When historic authenticity is important, traditional materials and techniques may be employed to recreate the appearance and performance of earlier caulking methods.

Etymology traces calk back through older English spellings of caulk, with usage evolving as sealing materials and methods advanced. Today, calk/calk and caulk/caulking are widely understood in woodworking and maritime contexts, though the preferred spelling varies by region and discipline. See also caulking, caulk, sealant, and shipbuilding.