Thread Locker Study
Thread locker generally comes in a very small tube and seems very expensive for the quantity I am buying. But I had been feeling like I needed plenty on hand, so I had been constantly adding to my collection.
Thread locker is usually very low in viscosity, so I had high hopes when I bought a stick of Loctite 248 medium strength blue from Enco last year. It was like a small tube of blue speed-stick deodorant and didn’t run at all. I tried applying it to one side of some 5/8″ bolts, thinking that the nut would spread it around. When I went to remove the nuts a week later, it seemed to have not done any thread locking at all. Perhaps that was because the nut hadn’t spread out the thread locker. So I tried it again, applying it completely around the bolt. 5 days later, nothing again.
I regularly use a thread locker when I assemble my multi-layered wall sculptures with 1/4-20 nuts and bolts. Each piece has a patina that needs to extend beneath its overlying piece. I can’t weld these pieces together because a) then I wouldn’t be able to get them apart b) the welding heat can cause delamination of the copper or discoloration of the patina and c) it would be difficult to incorporate spacers with a welding technique. I usually have at least 1/2″ between layers – a very cool visual effect.
So I was dismayed to hear that some of the 1/4-20 nuts with a red (permanent) thread locker had come loose on a wall sculpture that I’d shipped to California. True, it was 3 days constantly vibrating in the back of a truck – I would come loose too. But still, the nuts should have held.
Thread Locker Tests
Like many people, I tend to believe what companies tell us about their products. It pays to be skeptical, but it takes so much time to do testing, that sometimes I skip it. However, this seemed to be an emergency, so I made the extra effort to test my thread lockers. Here is the test I ran, in tabular form.
|Thread Locker Name||Cure Time||inch-pounds to loosen|
|Loctite Blue 242||30 days||less than 5|
|Prime Lok Blue 245||30 days||less than 5|
|Loctite Blue 248||30 days||less than 5|
|Permatex High Strength Red||30 days||less than 15|
|Permatex High Strength Red||2 days||less than 20|
|Loctite High Strength Red 271||30 days||less than 20|
|Loctite High Strength Red 271||2 days||less than 20|
|Loctite Medium Strength 242||30 days||less than 2|
|Loctite Medium Strength 242||2 days||less than 8|
|Permatex Pentrating Green||30 days||less than 2|
|Amazing Goop – Household||2 days||less than 2|
|Smart Coat 1K – clear coat||2 days||less than 1|
|Loctite Superflex Clear RTV||2 days||less than 1|
|Liquid Nails – Small Projects||2 days||less than 2|
|Gorilla Glue||2 days||less than 35|
|3M epoxy 420||30 days||less than 50|
|3M epoxy 460||30 days||less than 60|
|3M epoxy 110||30 days||less than 50|
Thread Locker Results Discussion
Surprising results. The first 30-day tests of the red (permanent) thread lockers were so poor that I re-did them with the 2-day test. I don’t know why I got disparate results on two of them. Still, less than 20 inch-pounds is not good enough for my purposes. And to have it work well sometimes and not others is not good.
The best test would probably be a 24 hour and/or 12 hour test. Usually you get the nuts on the wall sculpture on tight and then you want to be able to ship it out the next day.
I included Smart Coat 1K in the test because I have some of this clear coating in a jar and the jar lid is so hard to get off when the coating has dried. But the jar lid is 4″ in diameter – big size difference versus a 1/4-20 nut.
Do these thread lockers get old? I doubt it. Do they separate and have to be shaken before use? I don’t think so – no directions say to shake or stir well first. Do the bolts have to be cleaned with acetone first? I hope not.
My torque wrench is by K-D Tools, #2955, a beam type. I don’t have a calibrator, but it’s new and I hope it’s accurate. Like all beam torque wrenches, it is to zero before using and easy to read.
I now use only 3M epoxy for my thread locker, and paint it all around the bolt. Plus I torque all the nuts to 40 inch-pounds. It takes a little more time, but I am glad to do it for the peace of mind. I may also use Gorilla Glue for less critical applications.
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