Threadlock, is it reusable?

Specifically, if I remove a bolt with threadlock on (and where I think the threadlock is needed), then immediately do it up again, do I need to reapply threadlock? or will the threadlock already on the bolt/nut do the trick?

I wouldn’t rely on it.

No, you need to remove the old thread lock, degrease both threads (male and female) and apply new threadlock.
If doing the job properly.

What to remove it with? Wire brush?

Wire brush, picks & contact cleaner/IPA

I’m sure I’ve had new bolts in the past with some dried blue stuff pre applied that looked like threadlock.

How would this work then?

Can’t remember what the bolts came with, might not have been bike stuff but I’m 99.999999% sure they had blue stuff on the threads out the box.

…. any IPA or has it got to be Flowers?

I’ll get my coat….. 😉

I’m sure I’ve had new bolts in the past with some dried blue stuff pre applied that looked like threadlock.

How would this work then?

threadlock works by filling the gap between two threaded components, if pre applied (dry) then you are deforming this (its plastic basically) to squish it into the thread. When applied wet it flows into the thread giving a wider application and also forming to all the extra surface area of the full thread, so would work better (tho obviously the previous method works sufficiently enough).

From loctitie;

“LOCTITE threadlockers are single-component liquid and semi-solid adhesives. They cure at room temperature to a hard solid thermoset plastic when applied to metal fasteners and in the absence of air. The adhesive completely fills the gaps between mating threads to lock threads and ensure consistent clamp loads.”

I was using some threadlock on my rear axle as it seemed to work loose and needed re-tightening half way through a ride. A guy off MTBR (who actually makes axles for a living) suggested using Permatex Ultra Blue as it was grippy like a threadlock but was ok to undo and re-tighten and better in his opinion than a threadlock compound.

Have used some and so far seems good. Wheel’s been off and on a few times and it’s not worked loose at all.

What is the bolt you have holding in place?

Do people clean off and re thread lock rotor bolts ?

I know, I have never bothered, I am not dead yet but ?

Another survivor of re-used threadlock but depends on application I think. Hyrdo caliper mounts for instance I rarely bother cleaning up, the threadlock is so caked on can barely turn by hand, never had any problems over the years.

@aphex_2k it’s a specialized yoke-onto-shock mount. Apparently they upped the torque spec on these as they came undone a lot.