Q. What is the difference between Trempro 635 and Trempro 636 "Vulkem"?
A. Trempro 636, like all Vulkem is a traditional solvent-based polyurethane sealant, but with a very slow cure rate. It takes 4 hours for it to become tack free. With traditional polyurethane sealants, a slow cure rate is very important. The slower the cure, the higher the ratio of solvents to solids. The solvents are useful in cutting through any oil/grease that may be on the skin of the trailer. This gives better adhesion on aluminum that has been exposed to the elements. Traditional fast-cure sealants like Sikaflex 221 (tack free in 60 minutes) are better used in assembly-line production where speed is important and material conditions are controlled. Also, slower curing sealants are generally stronger than traditional faster curing sealants.
We recommend TremPro 636 especially when installing new panels when you need to buy a little extra time to make sure everything is positioned correctly.
TremPro 635, on the other hand, is a faster curing polyurethane sealant. It is tack free in 90 minutes. This makes it easier to use when speed is important. You won't have to worry about smudging it 3 hours after you apply it.
But TremPro 635 isn't a traditional fast cure sealant like Sikaflex 221. TremPro 635 uses new solvent-free SPUR (silane terminated polyurethanes) technology that gives it strength and adhesion equal to traditional slow cure polyurethane sealants. It is also a no VOC product.