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Blue vs red threadlocker

Updated: October 2026

You are holding a blue bottle and a red bottle, or a green one a chart from another country never mentioned, and you need to know which fastener each one is for. Blue vs red threadlocker is a strength choice, not a paint choice. Pick a medium grade you can undo with hand tools when you will service the joint. Pick a high-strength red or green only when you accept heat later. Peter F. compared the bottles in our [threadlocker comparison](/hub/diy-supplies/threadlocker) with Henkel's UK colour article and Loctite's UK consumer guide. He did not run a lab test. A qualifying purchase can earn us a commission at no extra cost to you.

You are holding a blue bottle and a red bottle, or a green one a chart from another country never mentioned, and you need to know which fastener each one is for.

Our top picks

Bäder Bäder B270Eco high green, 10 ml

Best overall

Bäder Bäder B270Eco high green, 10 ml
7.6/10about £5.45
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Bäder Bäder B243Eco medium blue, 10 ml

Rank 2

Bäder Bäder B243Eco medium blue, 10 ml
8.4/10about £5.39
View offer
kintsukuroi kintsukuroi medium blue, 50 ml

Preis-Tipp

kintsukuroi kintsukuroi medium blue, 50 ml
6.9/10about £8.88
View offer
On this page
  1. 1.What blue is for
  2. 2.What red is for
  3. 3.Where green fits
  4. 4.When the label disagrees with the dye

What blue is for

Blue, on the UK pages that define it, is the medium grade. Loctite's consumer guide points it at bikes and garden kit and says you remove it with hand tools. Henkel's UK article treats blue the same way. In this set the Bäder 10 ml medium blue, at £5.39 with 4.7 from 229 reviews, uses that word and that colour together, and UK reviews say buyers could still undo the screws. Bäder's B243Eco name is not a Loctite 243 certificate. On a larger thread, a review of the 50 ml Bäder blue says heat or extra leverage was needed. Blue is not a promise that a seized thread will spin off cold. The buying rules are on the threadlocker buying guide.

What red is for

Red, on Loctite's consumer page and on the RS guide, is the high-strength liquid. You remove it with localised heat and then tools. The consumer page describes heat of about 230 °C. That figure stays on that page. It is not a torch script. Nanoxa's bullet matches the split: medium blue comes off with hand tools, and high-strength red needs heat. It does not print the degree. sitarcmin's service bullet of -54 °C to 150 °C is a service band, not a removal temperature. Use red when you do not plan to undo the fastener, and when heat later is acceptable. A fairing bolt you will remove next winter is the wrong one. Brakes, steering, suspension, and fuel are a mechanic's decision before the dye matters. When you should not start the heat is on how to remove threadlocker.
Bäder Bäder B270Eco high green, 10 ml

Testsieger

Bäder Bäder B270Eco high green, 10 ml
7.6/10about £5.45
View offer

Where green fits

Green is the high-strength grade on Henkel's UK chart, removed with heat and hand tools. That article can treat a red bottle as a trademark rather than as the colour of the liquid. You cannot import one country's dye and ignore the strength word on the bottle in your hand. Bäder's high-strength 10 ml bottle is green, at £5.45, with 4.8 from 271 reviews. UK reviews say a little is enough and that heat loosens it. The 50 ml green title says high and the first bullet says medium, so that bottle has not picked a side. Purple is Henkel's low grade, but the purple Bäder listing says low and medium in one bullet.

When the label disagrees with the dye

Read the strength word when the dye and the cell disagree. Flintronic's £3.99 pair is titled blue and red, medium and high, and the colour cell says blue mid-strength only. The other Flintronic title says both strengths, and the colour cell says red high-strength. The clear Loctite tube is transparent and says Normal. If you will undo the fastener, buy a bottle that says medium, with a blue colour cell. If you will not undo it, and you can heat it later, a high-strength red or green is the same class of job, provided the bottle says high. Then follow how to apply threadlocker.

Common questions

Is blue always weaker than red?
On Loctite's UK consumer guide and the RS guide, blue is the medium grade and red is the high grade, so blue is the one hand tools are meant to undo. It is not a law for every dye. A blue bottle whose listing says high, or a listing that never states a strength, has not joined that chart. Judge the strength word on the page you are buying.
Why is high-strength threadlocker sometimes green?
Henkel's UK colour article uses green for the high-strength liquid and can treat a red bottle as a trademark. RS also describes green as high strength and low viscosity. Bäder's high 10 ml bottle in this set is green. Other brands here use red for the high grade. Green is not a mild version of red when the label says high.
Can you undo blue with a spanner?
That is the design of a medium blue on the UK guides, and kintsukuroi's bullet says common hand tools. Reviews of the Bäder 10 ml blue say buyers could still undo screws. A larger thread can need more force, which one review of the 50 ml Bäder blue describes as heat or extra leverage. Corroded threads are a separate problem from the dye.
What happens if you use red on a bolt you service?
You have put a high-strength lock on a fastener you wanted to open with tools. Nanoxa and the UK consumer guide both say that red side needs heat. You may still get it off, because RS says heat and tools can undo high strength, but you have made a later job harder. Use medium blue for the bolt you know you will service.
Is green the same job as red?
When both say high strength, yes: they are the heat-to-remove class, not the hand-tool class. Henkel UK puts green in that class. Nanoxa puts red in that class. They are not the same formula, and a green listing that also says medium, as the 50 ml Bäder bullet does, has not picked a side. Match the word, then the dye.
Which side should a bicycle or fairing bolt be on?
The medium side: a bottle that says blue or states medium and hand tools, if you will remove that bolt again. High-strength red or green is for a fastener you intend to leave and can heat later. If the colour cell names only one dye and the title names two, do not use that pair to decide a fairing bolt.

Related pages

Threadlocker medium strength comparison

Threadlocker

Best threadlocker for bolts you will undo with tools

Threadlocker buying guide: strength, colour and fill

How to apply threadlocker on a metal household bolt

How to remove threadlocker with tools or localised heat

Sources

Public UK sources on colour codes, cure, removal temperatures, COSHH and GB CLP. Listing prices, stars and review themes are from the amazon.co.uk extracts dated 15 October 2026. Prices move.

  1. Henkel UK, blue, green and purple threadlockers (retrieved 15 October 2026)
  2. Loctite consumer UK, how threadlocker works (retrieved 15 October 2026)
  3. Henkel, how to remove high-strength threadlocker (retrieved 15 October 2026)
  4. LOCTITE 243 technical data sheet (retrieved 15 October 2026)
  5. LOCTITE 270 technical data sheet (retrieved 15 October 2026)
  6. ISO 10964:1993, torque method (retrieved 15 October 2026)
  7. HSE, COSHH assessment (retrieved 15 October 2026)
  8. Control of Substances Hazardous to Health Regulations 2002 (retrieved 15 October 2026)
  9. HSE, GB CLP (retrieved 15 October 2026)