3M Scotch-Weld Urethane Adhesive 620NS, Black, 400 ml

3M Scotch Weld Urethane Adhesive 620 is a rapid setting, two part, polyurethane adhesive with low temperature flexibility and low shrinkage. These features make this urethane adhesive an ideal choice for bonding dissimilar substrates together, and in exterior applications, particularly in the general industrial, transportation, maintenance and repair, and construction industries. With an easy mixing, non sag formula you can be assured our adhesive will remain where you place it even when used on vertical surfaces. It is available in bulk or smaller Duo Pak forms. Two Parts, One Common Bond The mix ratio is 1:1 for quick, precise dispensing, and with a 20 minute working time there's ample opportunity for repositioning to keep projects on track. The adhesive reaches handling strength in approximately four hours and is fully cured in 48 hours (at 72F/22C). Unlike one part polyurethanes, this material has no depth of cure problems and cures throughout relatively quickly. Why Choose Urethane? Urethane adhesives are two part adhesives that are relatively flexible when cured, have excellent impact resistance and good adhesion to most plastics. They also bond well to woods, concrete and rubbers, but have reduced resistance to solvents and high temperatures. Uncured adhesive components are sensitive to moisture. Structurally Strong Polyurethane adhesives are part of the class of adhesives called structural adhesives, which also includes acrylic, cyanoacrylate, and others. Polyurethanes begin as reactive liquid polymers that undergo a chemical reaction when mixed, and then cure to form a solid plastic material. Once the two parts are mixed in their specified ratio, they begin the curing process and offer a limited working time where the adhesive can be applied and the two surfaces positioned as need. This work life lasts anywhere from a few minutes to a few hours.