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How to apply threadlocker

Updated: October 2026

The job goes wrong in two places: the liquid sits where the threads never meet, or you ride the bike at the ten-minute mark. This is how to apply threadlocker on a metal fastener you still expect to undo. Clean the thread, put the drops where the threads will engage, tighten once, and treat 24 hours as full cure. The bottle choice sits on the [threadlocker medium strength comparison](/hub/diy-supplies/threadlocker-medium-strength). Peter F. used amazon.co.uk bullets and Henkel’s UK 243 instructions, read on 15 October 2026. This is not a lab method. A qualifying purchase through our links can earn us a commission at no extra cost to you.

The job goes wrong in two places: the liquid sits where the threads never meet, or you ride the bike at the ten-minute mark. This is how to apply threadlocker on a metal fastener you still expect to undo.

Our top picks

Vigorder Vigorder blue 50 ml

Best overall

Vigorder Vigorder blue 50 ml
9.6/10about £7.99
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Bäder Bäder B243Eco blue 10 ml

Preis-Tipp

Bäder Bäder B243Eco blue 10 ml
9.4/10about £5.39
View offer
kintsukuroi kintsukuroi blue 50 ml

Alternative

kintsukuroi kintsukuroi blue 50 ml
9.0/10about £8.88
View offer
On this page
  1. 1.Clean the thread and pick the medium bottle
  2. 2.Bolt, nut, or blind hole
  3. 3.Fixture time is not full cure
  4. 4.When to stop

Clean the thread and pick the medium bottle

Old locker, thick oil and cutting fluid stop a new drop from wetting the metal. Henkel’s 243 how-to degreases, and below 5°C it names an activator for that grade, not a shopping list for every bottle here. Dry, bare metal is the starting point. Henkel describes Loctite 243 as tolerant of minor oil. Vigorder’s bullet says the threads should be clean and dry. Do not flatten those into one rule. If you turn a fastener after cure has started, clean it and start again. Pick the medium bottle before you unscrew the cap. In a two-colour pack the red bottle is the permanent one on the listings that say so. The difference is on blue vs red threadlocker. Do not return unused liquid to the bottle if the label says so.

Bolt, nut, or blind hole

On a through-hole, put the liquid on the bolt where the nut will cover it, not in a ring around the head. Tighten once, to the torque the manual already gave you. Threadlocker is not a substitute for that torque. In a blind hole, Loctite’s UK consumer guide puts the drops in the bottom so the screw does not push the liquid out with a pocket of air. A few drops are what UK reviews of the 5 ml Loctite 243 bottle describe. Squeeze-out on a brake rotor is a contamination risk, which the threadlocker for bike bolts page treats separately. sitarcmin says to tighten within three minutes. If you back the bolt off, clean it and dose again. The buying guide is where you check the bottle was medium strength.
Vigorder Vigorder blue 50 ml

Testsieger

Vigorder Vigorder blue 50 ml
9.6/10about £7.99
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Fixture time is not full cure

The first number on the bottle is not the moment you load the joint. kintsukuroi prints 10 minutes then 24 hours. sitarcmin prints 15–20 minutes then 24 hours. Vigorder and Nanoxa print 20 minutes then 24 hours. The Flintronic bullets print no clock. Henkel’s UK 243 page uses about 10 minutes to fixture and about 24 hours to full cure. Use the longer number before the bike or the car goes back into service. If your bottle has no clock, 24 hours is a rule of thumb, not a test of that liquid. Do not rotate the fastener to check it during that day. A turn after the film has started shears it. Clean both threads and begin again.

When to stop

Stop before you lock a brake, a steering joint or a suspension fastener that the manual does not name. A UK review of a caliper bolt is not permission. Stop if the thread is plastic, if the joint holds pressure, fuel or brake fluid, or if a high-strength bottle will not move near fuel, paint or a sensor. At work, COSHH sits with the employer. GB CLP is the label on the bottle, not the Amazon title. A leaked cap is a faulty supply, not a dosing tip. The sequence stays short: clean, dose the engaged threads or the bottom of a blind hole, tighten once, wait 24 hours.

Common questions

Do you put it on the bolt or in the nut?
On a through-hole, put it on the bolt where the nut will sit, then run the nut on. Wetting only the outer face of the nut leaves the engaged threads dry. In a blind hole, put the drops at the bottom of the hole so the screw does not push the liquid out with a pocket of air. A few drops are enough. A ring around the bolt head does not lock the thread.
How long until you can use the bike or the car?
Wait for the full cure, which is 24 hours on the bullets that print it and on Henkel’s UK 243 page. The 10, 15–20 or 20 minute figures in this set are fixture times. They mean the liquid has started to hold, not that you should load the joint. If the bottle prints no clock, treat 24 hours as the rule of thumb and do not ride at the shorter number from a different brand.
How much do you use?
Enough to wet the threads that will be engaged, which UK reviews of the small Loctite 243 bottle describe as a few drops. More than that squeezes out and does no extra locking. Do not return unused liquid to the bottle if that bottle says so, as Vigorder’s bullet does. A half-full bottle, where the seller says the air gap is intentional, is not a cue to use twice as much.
What if you have to turn the bolt again while it is curing?
Clean both threads and start again. A turn after cure has begun shears the film, and a second wet coat on top of that film is not a repair. Do it before the part goes back into service, not after a test ride. If the bolt is already a high-strength lock beside fuel, paint or a sensor, stop and get a professional rather than forcing it.
When do you stop and get a professional?
When the fastener is a brake, steering or suspension bolt and the manual does not name the grade, or you cannot apply the torque it states. Also when the joint holds pressure, fuel or brake fluid, when the thread is plastic, and when a high-strength lock will not move near fuel, paint or a sensor. A household cover screw is the job this sequence is for. A safety-critical joint is not.

Related pages

Threadlocker comparison

Threadlocker medium strength

Best medium strength threadlocker for a bolt you undo

Threadlocker for bike bolts you still need to service

Blue vs red threadlocker for a bolt you will service

Medium strength threadlocker buying guide for a bolt

Sources

Henkel, the Health and Safety Executive, ISO 10964 and the Consumer Rights Act 2015, plus the amazon.co.uk listings read on 15 October 2026. Prices move. Nothing was torque-tested in a lab.

  1. Henkel UK, LOCTITE 243 (retrieved 15 October 2026)
  2. Henkel UK, choosing a threadlocker (retrieved 15 October 2026)
  3. Henkel GB SDS 817149, 11 June 2026 (retrieved 15 October 2026)
  4. HSE, GB CLP (retrieved 15 October 2026)
  5. HSE, COSHH (retrieved 15 October 2026)
  6. ISO 10964:1993 (retrieved 15 October 2026)
  7. Consumer Rights Act 2015 (retrieved 15 October 2026)
  8. Permatex medium strength threadlocker blue (retrieved 15 October 2026)
  9. amazon.co.uk listings, example Bäder B0CFR456YL (retrieved 15 October 2026)