Dow Corning ® Contractors Weatherproofing Sealant (CWS) Medium-modulus silicone joint sealant. Dow Corning ® Contractors Weatherproofing Sealant (CWS) is a one-part, moisture cure, medium modulus sealant that provides durable, flexible, watertight joints and offers outstanding unprimed adhesion to most non-porous substrates. It is specifically developed for sealing dynamically moving joints. Dow Corning ® Contractors Weatherproofing Sealant (CWS) used sealing dynamically moving joints such as expansion and control joints, concrete panel joints, tilt-up panel joints, curtainwall joints, perimeter caulking (windows, doors, panels, EIFS, bedding of mullions, panels, and frames, etc.) Color: Light Bronze Contents of Sausage : 20 fl oz (590 ml)