Open Cell, No Skin, Non-Gassing Rod is Compatible With All Cold-Applied Sealants Controls Depth of Sealant and Acts as a Bond Breaker Soft, Compresses Easily CRL Open Cell Backer Rod is a soft, round, and easily compressible open cell polyurethane foam. Open Cell Backer Rod is not adversely affected by dynamic joint movement, and its inherent flexibility applies itself to joint variations very easily. It is ideal for use in situations where joint damage has occurred. It eliminates potential sealant failures due to out gassing that occurs when the "skin" of closed cell backer rod is punctured. The black color helps to disguise the backer rod in certain joint applications. CRL Open Cell Backer Rod can be used in temperatures from -65° to 400°F(-54° to 204°C). It is highly recommended for use with high performance sealants such as silicones and urethanes. CRL Open Cell Backer Rod should be used only in vertical and horizontal wall joints. It is not suitable for horizontal traffic joint surfaces like pavement joints. Proper size selection of CRL Open Cell Backer Rod is important as it controls the depth of the sealant bead. It must be oversized (50%) to fit tightly into the joint, and function as a bond breaker to prevent bottom-side adhesion of the sealant. New joints must be cleaned thoroughly, removing any concrete form-release agents, curing compound residue, or any other foreign materials. To ensure a good sealant bond, joints must be clean and dry when the sealant is installed. If old joints are being repaired, all old sealant or filler must be removed. Wire brushing and air blasting are very effective in removing old caulk residues. If an air compressor is used, it must be equipped with traps for the removal of oil and moisture.