Threadlockers, Epoxy and Sealants

Blue or red: how permanent should the bond be?

Blue threadlocker is medium strength: it keeps fasteners from vibrating loose yet comes undone with ordinary hand tools. Red is high strength and permanent, and usually needs heat from a torch to release, so reserve it for parts you never plan to remove. Apply to clean, dry threads and avoid plastic parts unless the label allows it. Small tubes suit a few fasteners; a 50 ml bottle suits repeated use.

Cartridges, mix ratios and the dispenser that fits

Caulk and sealant come in cartridges that fit a standard caulk gun, with 10.3 ounces a common size. Two-part epoxy comes in dual cartridges with a fixed mix ratio, such as 10:1, and needs a dispenser or plunger made for that ratio and a mixing nozzle. Near oxygen sensors, choose an RTV silicone labelled sensor-safe, since some cure by releasing acetic acid vapor.

Questions about Threadlockers, Epoxy and Sealants

Can I reuse a bolt that already has threadlocker on it?

Yes. Clean off the old residue with a wire brush and solvent, let the threads dry, then apply fresh product. Cured threadlocker left on the thread can stop the new film from bonding properly.

How long before a threadlocked bolt can take load?

Most set to handling strength within minutes to an hour and reach full strength after about a day, but cold or inactive metal surfaces slow the cure. Check the label for the maker's figures.

What is the difference between a threadlocker and a thread sealant?

A threadlocker stops fasteners from loosening, while a thread sealant seals threaded pipe joints against leaks. Some formulas do both. Check the label for the intended use and the fluid it will contact.