Also known as neutral-cure sealants, these won't discolor copper, brass, and concrete. They’re non-sagging, so they won't drip from vertical and overhead surfaces. Made from silicone rubber, sealants are RTV (room-temperature vulcanizing).

Elongation and joint compression/expansion tolerance indicate flexibility—the higher the values are, the more joint movement sealants can sustain. Sealants that are good for joining dissimilar materials also work well in environments with wide temperature fluctuation.