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Differences abound between caulk, sealant

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The terms “caulk” and “sealant” often are used interchangeably, but they are fundamentally different. Caulks are used to fill a gap or crack and cannot accommodate much movement. Sealants are more flexible; they fill a void and bond to the substrate while functioning as a barrier to water, air and other substances. Additionally, polyurethane sealants offer higher-performing properties than caulking agents.

Polyurethane sealants are available in one-component (1K) or two-component (2K) formulations, and the prepolymers in the sealants' formulation provide the physical properties. Recently developed 1K polyurethane sealant technology, based on silane-terminated prepolymers (STPs), eliminates the potential for the sealant to foam when in contact with moisture. New research has been conducted to compare STPs with other formulations to determine benefits and performance.