Threadlocker Colors Explained: Blue vs Red vs Purple vs Green

Vibration loosens bolts. Threadlocker stops that by filling the gaps between threads and hardening into a plastic that holds the fastener in place. The color tells you how strong it is — and how hard it will be to remove later.

What each color means

Color	Strength	Typical use	Removal
Purple	Low	Small screws and adjustment screws	Hand tools
Blue	Medium	Most nuts and bolts that need to come off for service	Standard hand tools
Red	High	Permanent fasteners such as studs and suspension bolts	Heat plus hand tools
Green	Wicking	Pre-assembled fasteners; penetrates from the outside	Varies by product

How to use threadlocker the right way

1. Clean the threads with brake cleaner or a parts cleaner and let them dry.
2. Apply a few drops to the bolt threads where the nut will sit.
3. Assemble and torque to spec.
4. Allow curing time before putting the part under load. Check the label for cure times.

Removing a red threadlocker fastener

Red threadlocker is designed to stay put. To remove it, heat the fastener with a heat gun or torch (following the product label for temperature), then remove it while it is still hot. Take care around fuel lines, wiring and plastics.

Blue is the safe default

If you are unsure, blue medium-strength threadlocker is the right choice for most automotive jobs. It holds against vibration but still comes apart with normal tools.

Permatex products we carry

RPS Distributors stocks Permatex threadlockers, gasket makers, adhesives and sealants, plus brake cleaner for prep. Browse the Auto Accessories collection and Sealant, Stop Leak & Chemicals collection.

Request a wholesale quote or call 1-855-498-7509.