Loctite retaining compounds loctite 1803365 loctite 638 has been designed for the bonding of cylindrical fitting parts particularly where bond gaps can approach 025mm it cures when confined in the absence of air between close fitting metal surfaces and prevents loosening and leakage due to shock and vibration loctite 638 not only works on active metals but also on passive substrates exhibiting robust cure performance it offers high temperature performance and good oil tolerance and t