3M™ Scotch-Weld™ Instant Adhesive CA4 is a low viscosity instant adhesive. Our CA4 instant adhesive is formulated to give exceptional strength and impact resistance on a wide variety of substrates, including plastics and rubbers. Once applied, the glue has fast handling time and cure to keep jobs moving quickly. - 3M Scotch-Weld instant adhesive CA4 has good adhesion to a variety of substrates, including most cured rubbers, plastics and metals. This high strength, multi-purpose adhesive is a great option for those looking for an easy-to-apply adhesive that provides a very fast setting bond.