Loctite 101

sleepless · June 12, 2022, 4:33pm

There’s a few threads on this, but this question gets asked constantly by new and experienced builders. This wiki should be a one stop shop for those questions. Please update as you see fit.

Editor’s request: Stop referring to threadlocker by colors. As you can see below, there are many grades, each with very specific properties and applications, in many different bottle colors and liquid colors. There’s hundreds more that aren’t listed here. Colors are vague and spread confusion more than help.

SELECTION GUIDE

Expand Table

Application	Esk8 Use	Part	Strength	Color	Features	Size	Disassembly	Cure Time	Op Temp
THREADLOCKING (screws)	n/a	Loctite 222	Low	Purple	Easily removable with normal tools		Easy	24 hrs	150 C (300 F)
		Loctite 242	Medium	Blue	Disassembly with normal tools		Normal	24 hrs	180 C (360 F)
	General purpose medium, truck fasteners & nuts, enclosure fasteners	Loctite 243	Medium	Blue	242 new formulation, with improved oil/dirt resistance		Normal	24 hrs	180 C (360 F)
		Loctite 262	High	Red	Disassembly with direct heat		Heat, 250C	24 hrs	180 C (360 F)
	General purpose high, motor mount fasteners	Loctite 263	High	Red	262 new formulation, with improved oil/dirt resistance		Heat, 250C	24 hrs	180 C (360 F)
	Hanger axles	Loctite 290	Medium/High	Green	Wicking, for preassembled fasteners		Normal	24 hrs	150 C (300 F)

RETAINING (shafts)		Loctite 638	High	Green	High viscosity, use on larger gaps approaching 0.25mm	0.25mm gap	Heat, 250C	24 hrs	180 C (360 F)
	Pulleys/gears/sprockets/keys onto motor shafts	Loctite 648	High	Green	Low viscosity, press/close fit cylindrical parts (100% cure in 7 days)	0.15mm gap	Heat, 250C	24 hrs	175C (350F)
		Loctite 680	High	Green	Low viscotiy, loose fitting parts, slip fit. Best resistance to dynamic, axial, radial loads. (100% cure in 7 days)	0.2mm gap	Heat, 250C	24 hrs	150 C (300 F)

Bolded items are recommended to have in your toolbox

HOW TO APPLY THREADLOCKER CORRECTLY

Common Application Mistakes

Failing to clean the fastener and the threaded hole
Dirt, grease, and oil residue are all enemies of threadlockers. To get the full cure and full holding power of your threadlocker, the male and female threads need to be completely clean and dry. Don’t shortcut this step.
Using too much threadlocker:
Threadlockers only need to be applied to the first few threads on a fastener. Tightening the fastener will spread the threadlocker evenly. Using too much threadlocker can cause excess to spill out and migrate to unwanted areas.
Not waiting for the proper cure time:
Threadlockers provide excellent holding power - but only after they’ve had time to cure. Typically, threadlockers achieve ‘fixture strength’ in 20 minutes and fully cure in 24 hours. Fixture strength means it’s OK to put your assembly back in service, but a full cure is when you’re getting the full holding power of the threadlocker.

DISASSEMBLY & CLEANING

[credit: @rusins ]

To remove pulleys, sprockets, and gears from motor shafts:
Use a pulley remover tool (aka gear puller). They apply way more force than you could by hammering at them.

A wiper arm puller like the Lisle 54150 has thin arms to get into especially tight spacers.

To clean threadlocker off fasteners:
Acetone appears to dissolve blue and red threadlockers quite well. Just use a paper towel and your nails to scrape it off, should work. A wire brush can also be helpful.

To disassemble fasteners with red (high strength) threadlocker:
You need a heat gun. Once you heat it to a certain point and turn the bolt a little bit, it should be possible to then unscrew it completely.

To disassemble fasteners with green (high strength) threadlocker:
You need a butane torch. Even then it might not want to come off. All I can say to you is: good luck

PLACES TO PURCHASE

Links and prices as of May 2021
Google shopping is your friend, but the above links are a good start. It will take you forever to finish a small bottle, let alone the 50ml bottles.

REFERENCES - Charts

[credit: @PixelatedPolyeurthan and @frankthedragon]

REFERENCES - Forum Threads

REFERENCES - Henkel Loctite Corp information