Everbuild butyl rubber sealant 145 everbuild 145gy 145 butyl sealant is a traditional permanently plastic one component sealant based on polybutene that provides an effective weatherproof seal in a variety of exterior and interior applications 145 butyl sealant forms a skin in 24 hrs but remains permanently plastic underneath the sealant accommodates joint movement of 5 is over paintable and exhibits good uv and chemical resistance everbuild 145gy butyl rubber sealant c3 310ml 145