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High strength threadlocker: which bottle to buy

Updated: October 2026

A cover bolt that works loose every few weeks is why people buy a high strength threadlocker. Buy it only for a metal joint you will not open with a spanner. If you will service the fastener, read [high strength versus medium threadlocker](/hub/cutting-tools/threadlocker-high-strength/sub/threadlocker-high-strength-vs-medium) first. This page decides metal, temperature and fill. The GBP table from amazon.co.uk on 15 October 2026 stays on the [high-strength threadlocker comparison](/hub/cutting-tools/threadlocker-high-strength). Named picks are on the [best high-strength threadlocker](/hub/cutting-tools/threadlocker-high-strength/sub/threadlocker-high-strength-best) page. Leaks and heat are on [how to remove threadlocker](/hub/cutting-tools/threadlocker-high-strength/sub/threadlocker-high-strength-removal). There was no lab test.

A cover bolt that works loose every few weeks is why people buy a high strength threadlocker. Buy it only for a metal joint you will not open with a spanner.

Our top picks

Loctite Loctite 270 50 ml

Best overall

Loctite Loctite 270 50 ml
8.4/10about £11.50
View offer
Realth Realth 10 ml × 3

Alternative

Realth Realth 10 ml × 3
6.5/10about £8.99
View offer
sitarcmin sitarcmin 50 ml + 50 ml

Best value

sitarcmin sitarcmin 50 ml + 50 ml
8.1/10about £8.99
View offer
On this page
  1. 1.Buy high strength only if you will not undo it
  2. 2.Metal, temperature and a published torque
  3. 3.Fill, a half-full bottle and a real leak
  4. 4.Read the words, not the cap colour

Buy high strength only if you will not undo it

High strength is for a stud, a gearbox fastener or a pump bolt that should stay shut. Henkel’s UK chooser treats Loctite 222 as a low-strength purple grade for small threads up to M12, Loctite 243 as a medium blue grade up to M18, and Loctite 270 as a high-strength green grade up to M20. That split is the manufacturer’s guidance, not a law and not a measurement from this desk. Low and medium grades are the ones Henkel says come off with hand tools. High strength may need heat, and Henkel’s own pages do not agree on one temperature. If the cover comes off at the next service, a permanent bottle is the wrong purchase. A thread film is not a bearing retainer. One UK reviewer found a strong grade did little on an axle that rocks.

Metal, temperature and a published torque

Loctite’s UK consumer guide limits this liquid to metal nuts and bolts and says it will not work on plastic. Realth and Nanoxa still print a materials line that says plastic, while their bullets talk about metal fasteners. Do not coat a plastic thread because of that line. Stainless, aluminium and plated steel can cure slowly. Henkel names activators SF 7649 or SF 7240 for a Loctite 270 bead that stays wet, or a workshop below 5 °C. That note is for 270 only. The only published torque here is 33 N·m breakaway and prevail for Loctite 270, on Henkel’s November 2024 sheet, to ISO 10964, on M10 steel after 24 hours at 22 °C. NSF P1 registration 123006 is that grade only. Do not move either figure onto a red bottle or onto Abnaok’s 243 and 271 title. Service ranges printed on the other bottles are listing sentences, not a hot test from this comparison.
Loctite Loctite 270 50 ml

Testsieger

Loctite Loctite 270 50 ml
8.4/10about £11.50
View offer

Fill, a half-full bottle and a real leak

A half-full bottle is normal when the listing says the empty half is air, so the anaerobic liquid does not cure on the shelf. Nanoxa, sitarcmin and GOLDEROC print that explanation. A cap that has dumped liquid into the bag is a different fault. Do not pour leaked liquid back into the bottle. Loctite 270 here is one 50 ml tube at about £11.50. Titled 50 ml twins run from about £7.99 (Abnaok) to about £12.99 (Nanoxa). Realth is 10 ml times three. One Flintronic listing states no fill at about £3.99. The other is titled 2 × 5 ml. Abnaok’s volume line and the 2.0 gram unit count disagree with the 2 × 50 ml title. sitarcmin’s unit count says 200.0 millilitres against 50 ml + 50 ml.

Read the words, not the cap colour

Read four things on the amazon.co.uk title before you buy. First, the words high, medium or low, because red, blue and green are not one code on every bottle in this set. Second, the millilitres, and whether a second line contradicts them. Third, whether the brand is Henkel or a seller using Loctite-style numbers. Abnaok’s title says 243 and 271, and the manufacturer is Abnaok. Fourth, the materials line. If it says plastic or wood and you are locking a steel bolt, you are trusting the bullets rather than the spec.

Common questions

Do I want high strength if I will undo the bolt with a spanner later?
No. High strength is for a metal joint you do not plan to open. Henkel’s UK chooser puts hand-tool removal on the low and medium grades, 222 and 243, and treats 270 as the grade that may need heat. If the cover comes off at the next service, choose medium.
Why is Loctite 270 green when other high-strength bottles here are red?
Loctite 270, ASIN B0068NKI5A, is Henkel’s green high-strength grade in this set. Most of the other listings use a different habit: red for permanent and blue for a joint you can undo with tools. Green is also the colour Henkel uses for wicking grade 290, which is not one of these eight bottles. Read the words high strength on the title, not the dye.
What temperature should I believe: Henkel, 150 °C or 220 °C?
Use the sentence on the bottle in your hand. Henkel’s UK page for Loctite 270 quotes −55 °C to 180 °C, and also a typical continuous range of −55 °C to +150 °C. sitarcmin’s bullet says −54 °C to 150 °C. GOLDEROC’s bullet says −54 °C to 220 °C. None of those was a hot test here.
How much liquid do I need: 5 ml, 10 ml or 50 ml?
A 5 ml or 10 ml bottle is enough for a few small screws. Realth is 10 ml of each of three strengths. One Flintronic title is 2 × 5 ml. A 50 ml bottle, or a 50 ml plus 50 ml twin, is the fill for several larger studs. Check that the volume line agrees with the title before you treat a low price as more liquid.
Can I treat an Abnaok bottle numbered 243 and 271 as Loctite?
No. The brand on that listing is Abnaok, not Henkel. The numbers 243 and 271 do not transfer the 33 N·m figure, NSF P1 123006, or Henkel’s note on passive metals. One UK reviewer could not tell the strengths apart because the labelling was in Chinese. The volume line and the 2.0 gram unit count also disagree with the 2 × 50 ml title.

Related pages

How to apply threadlocker

High-strength threadlocker

Best high strength threadlocker: top pick and value

How to remove threadlocker when the bolt will not turn

High strength vs medium threadlocker, before colour

Sources

Sources from the research digest. amazon.co.uk listings in this comparison were read on 15 October 2026. We did not run a laboratory test.

  1. Henkel UK, LOCTITE 270 (retrieved 15 October 2026)
  2. Henkel TDS, LOCTITE 270, November 2024 (retrieved 15 October 2026)
  3. Henkel UK, choosing a threadlocker (retrieved 15 October 2026)
  4. Henkel UK, blue, green and purple threadlockers (retrieved 15 October 2026)
  5. Loctite consumer UK, how threadlocker works (retrieved 15 October 2026)
  6. HSE, COSHH basics (retrieved 15 October 2026)
  7. HSE, GB CLP (retrieved 15 October 2026)
  8. Consumer Rights Act 2015, section 9 (retrieved 15 October 2026)