OSI RF-140 Roof & Flash Sealant is manufactured using a special synthetic rubber and select cuts of asphalts. By combining these two materials, the natural tendency of hardening and softening generally associated with asphalt is modified considerably with the rubber. This allows OSI® RF-140™ to cure into a tough, rubbery stage which will expand and contract more readily during temperature variations. In addition, the adhesion characteristics of the asphalt are augmented with a stable tackifying resin which will provides a lasting and flexible bond to most surfaces. Unlike other roofing cements, OSI RF-140 can be applied at temperatures between 20°F (-6.67°C) and 90°F (32°C) without difficulty in extrusion. Also, it resists the cracking which is common to most types of plastic roof cements.