SQ PU Sealant Description SQ PU Sealant is low modulus, one component, class A Polyurethane sealant. When cured it will form a tough, flexible seal capable of cyclic expansion and compression movement of 100% (+ 50%) of original joint width. SQ PU Sealant is virtually unaffected by normal weathering conditions such as rain, sunlight, snow, sleet, ultraviolet radiation, ozone, atmospheric contamination, and pollution. Its excellent weatherability enables it to retain its original properties after years of exposure; refer to the.