The Difference Between Red, Blue, Green and Purple Threadlockers

    July 11, 2013

Ever get confused about which threadlocker to use? Do you know what the differences are between the red, blue, green and purple threadlocker? You aren’t alone – we here at Henkel hear this question a lot and are here to tell you the difference.  

Loctite Threadlockers

To make it simpler for the consumer, our products are available in many different grades to cater to a broad array of applications, from auto maintenance and boat maintenance to a wide rande of household product repair. These different grades are color-coded to help you identify one threadlocker from another  The color refers to the actual substance, but all the bottles are red in color. The red bottle is actually a Loctite trademark; it’s what visually distinguishes Loctite® threadlockers from any other brand.  

So what is the difference between the Red, Blue, Green and Purple threadlocker?

red threadlockerLoctite® Red Threadlocker is the highest strength. This product cures fully in 24 hours and is available in both a liquid and as a semisolid anaerobic. The red products are so powerful that they require heat to be disassembled. A primerless grade red threadlocker is also available.  

[You might also be interested in: How to remove Red Threadlocker]

blue threadlockerLoctite® Blue Threadlocker is of medium strength. Again this product cures fully in 24 hours and can be dissembled with hand tools.  In addition to being available in a liquid and a semisolid, there is also Loctite® QuickTape® 249™ Threadlocker; the one and only of its kind globally. A primerless grade blue threadlocker is available as well.

[You might also be interested in: Blue Threadlocker Basics]

Green threadlockerLoctite® Green Threadlocker is recommended for locking preassembled fasteners, e.g. electrical connectors and set screws. The product is categorized as medium-to-high-strength for wicking. It is also available in a liquid form, cures in 24 hours and can be removed with heat and hand tools.

purple threadlocker

Loctite® Purple Threadlocker, also known as Loctite® 222™, has become one of our most successful products.  Loctite® 222™ cures in 24 hours. It can also be used on low-strength metals such as aluminum and brass.  This offers a lot of flexibility to the user.  Find customer testimonials and more information on our purple threadlocker in “When and Why to Use Purple Threadlocker“.

All threadlockers have a broad temperature resistance of -65°F to 300°F, some going up to as high as 650°F.

Threadlockers were Loctite’s first product line; they combine a mix of complex chemistry and engineering. Simply put, this product is an anaerobic adhesive applied by drops to the threads of fasteners. It then cures to a hard thermoset plastic that locks the threads together. They are used only for metal to metal applications.

If you are still unsure about which threadlocker to use, on which applications, download our FREE “Do it Right” User’s Gude

For more information on Loctite® threadlockers, including resources and product selector charts, click here


You might also be interested in: Common projects that Utilize Threadlockers

About the Author, Kelly Turner

Kelly Turner has been with Henkel 4 years and involved in the automotive aftermarket for 3 years. She was previously a Key Account Manager for Vehicle Repair & Maintenance, Maintenance, Repair and Operations, Solar, and Defense markets. Kelly graduated from Bryant University in Smithfield, RI with a Bachelors Degree in Marketing. In Kelly's free time she helps operate a family owned farm and equine breeding facility and has been a competitive horse back rider for over 25 years.

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45 responses to “The Difference Between Red, Blue, Green and Purple Threadlockers”

  1. Wendell Miles says:

    Thanks, good article! I broke a wrench on a driveshaft fastener, when I finally got it undone I saw the red Loctite on it… Wish I would have read this first!

  2. Bill M says:

    I have loc-tited two pieces of gun metal together the green type is there any solvent like naptha or mek that could desolve the loc-tite?

  3. Kelly Matson says:

    Thanks Wendell! I’m glad you enjoyed it.

  4. Kelly Matson says:

    Hi Bill. Thank you for your question.

    Methylene chloride will cut anaerobic, but typically is only used to clean gasketing surfaces after things have been disassembled. To disassemble, heat may be the best option. Over 450 F. Disassemble while hot. Keep in mind that as heat is applied and the strength of the product weakens it may not be always necessary to heat product over its temperature rating to disassemble. If you try MEK, it will most likely take several days of saturation to loosen up the assembly.

    I hope this helps. And thanks for reading.

  5. richard clark says:

    i am in the process of restoring a valuable antique engine block Many of the head bolt threads are stripped I need to use threaded inserts for repair since the goal is to use original diameter head bolts The head bolts are exposed to the cooling jackets around the cylinder walls and the inserts need to remain locked from turning as well as seal the coolant which is under pressure What would be the best item in your product line to use? thanks very much

  6. Kelly Turner Kelly Turner says:

    Hi Richard. Thank you for the question! First, make sure actual thread inserts are used, not Helicoils. Then make sure the tapped holes are very clean, solvent washed with a non-residue solvent (like acetone, IPA, or Loctite Pro Strength Parts Cleaner) and blown out. I would then use a red high strength product like Loctite 263, 271, 272, or 277 to install the inserts. Apply both in the holes (female side) and on the outside (male) threads. Locking in studs into the inserts would be better than bolts, but if the engine used bolts originally and that look is desired, I would suggest Loctite Head Bolt and Water Jacket sealant be used to install the head bolts.

    Good Luck!

  7. richard claark says:

    Thanks for the quick reply and detailed information. I have 271 already and just ordered the 1158514 head bolt and water jacket sealer. That product looks like exactly what I need. Much thanks!

  8. Jane says:

    good article just 1 comment if you talk about the red loctite first then in your pic why not put the picture in the correct order makes it easier for people to understand and relate too. Have seen this help millions of people relate to a pic in order of appearance

  9. Kelly Turner Kelly Turner says:

    Thank you for the feedback Jane! And we are glad you enjoyed the article.

  10. Karen Mattson says:

    We use green Loctite 290-31 to lock our screws into the printhead. Sometimes the screw breaks off. If we try to get it out using a tool the threads get stripped and the whole printhead is then useless. We can’t use heat because it will damage the printhead. This is a $300 part and we hate to have to scrap them. Is there anything that will dissolve the Loctite without causing damage?

  11. Kelly Turner Kelly Turner says:

    Hello Karen! Thank you for the question. In most cases, methyl ethyl ketone (MEK) can be used to dissolve the substance. If you’d like more details, feel free to call 1-800-LOCTITE to speak directly with our technical experts. Let me know if you have further questions. Thanks again!

  12. David C says:

    Is there any solvent that can dissolve Loctite threadlocker Red 271? Will MEK work?

  13. Loren Nauss Loren Nauss says:

    Hello David, thanks for your question. I have always recommended Methylene Chloride for breaking down and removing anaerobic but MEK will also work. Heat is also an option. Let me know if you have further questions or call 1-800-LOCTITE to speak to someone from our technical support team about your specific application needs.

  14. Ken Todd says:

    Is there a shelf life on red Loctite? i have a bottle of 271 that I’ve been using for years, seems to work OK.

    TIA, Ken in Alberta

  15. Kelly Turner Kelly Turner says:

    Hi Ken, thanks for your question. There is a “use by” date on all of our products. That date is the point we warranty performance based on internal testing. After this point, we can no longer guarantee the performance. The shelf life is set for each product individually based on its chemistry and specific formulation, and is verified by physical testing. We cannot say exactly what goes out of specification for each material, so we don’t recommend knowingly using out-of-date product. If you have inadvertently used expired product, the best thing to do is self-certify by testing some of the parts that were put together using the expired material to ensure that it has performed to your specifications. I hope that helps! Thanks again for reaching out.

  16. Ryan says:

    Ive read through the different colours of Loctite, however I am still unsure of which one to buy. I am going to use it for holding 10mm bolts secure on my bed. Thanks

  17. Mike Oliveira Mike Oliveira says:

    Hi Ryan, thanks for your question. I would recommend our blue threadlocker for your application. Please let me know if we can help further, or feel free to call us at 1-800-LOCTITE.

  18. Mike Saliga says:


    G10 to std SS helicoil. Looking for alt for a long lead short shelf life product. Any Alt available?


  19. Kelly Turner Kelly Turner says:

    Hi Mike, thanks for your question. I would recommend LOCTITE EA E-20HP Epoxy Structural Adhesive. You can find more information on it, including technical data sheets, here: If you have more questions, feel free to call us at 1-800-LOCTITE.

  20. Alex says:

    Hi, I am a blow mold designer. I need to know which type of lock-tit can be used for padding an opened water channel. It should with stand water pressure of 5bar.

  21. Richard DePolo says:

    I need to Loosen a 6/32 screw in Titanium that is held in place with Loctite 272.
    I really do not want to use heat to loosen for fear of changing the characteristics of the metal.
    IT is in a tight spot. Is there some sort of loosening agent i can use, such as Acetone.
    Again i do not want to cause any damage to the parts.Thank You

  22. Jeff says:

    We manufacturer a bench top lab centrifuge which is subject to internal vibrations. The aluminum rotor head mounts on the motor shaft with a pair of 10-24 alloy steel set screws. The rotor head may need to be removed for replacement, if required.
    What Threadlocker should be used on the 10-24 set screws in production?
    Thank for your feedback … Jeff

  23. Mike Oliveira Mike Oliveira says:

    Hi Alex, we would need more information to give you a suggestion here. Can you call our technical support team at 1-800-LOCTITE? Thanks, Mike

  24. Mike Oliveira Mike Oliveira says:

    Hi Richard,

    Acetone is probably not strong enough to break down the threadlocker. A strong solvent like MEK can help, but it may have trouble getting to the threads.


  25. Mike Oliveira Mike Oliveira says:

    Hi Jeff, I would recommend a low strength threadlocker like LOCTITE 222 for this application. Thanks, Mike

  26. John says:

    Hi Kelly, I’d like your opinion on a project I’m working on. I have a possible use for Loctite red but the 2 smooth steel round parts have no threads, they slide very tightly into each other with very little to no air space between parts, so much so the parts do not wiggle, but do rotate when torque is applied. I need a permanent bond between the parts which can withstand torque forces. Do you think Red is a good choice to “bond” these two parts? I also need about 5 minutes of work time; how long before Loctite red sets?

  27. Mike Oliveira Mike Oliveira says:

    Hi John, thanks for your question. I would recommend Loctite 648 Retaining Compound for this application. It can handle up to a .006″ gap and is rated for 355 F. Thanks, Mike

  28. Tim May says:

    Hello, I am using Locktite 243 on a steel part with steel fasteners. The fasteners are torqued to 55 ft Lbs. Part has high shock load (hydraulic shear for metal). Mfr recommends checking torque of fasteners after 500 cuts. Will checking the torque of a tight fastener that uses Locktite 243 affect the strength of the bond? Will the fastener tend to loosen after the torque value is checked 3 or 4 times?


    Tim May

    • Brandon Gearing says:

      Hi Tim,

      If a fastener is moved after full cure, all locking strength is lost and only prevailing torque is left. If the fastener is disturbed during cure the amount of torque loss can’t be accurately predicted.

      The suggested method of checking the quality of fastener locking strength is to assemble a number of fasteners in actual test parts and determine the strength variation for all fasteners. From these statistics, calculate 75% of the LOWEST value obtained and use that figure to test fasteners in actual parts. This should insure proper locking strength is obtained WITHOUT moving the fastener. We would suggest sampling 20 fasteners for this test.

  29. Christopher J Coulson says:

    Helpful thank you.

  30. Andy says:

    Hello, I’m installing a thread insert into a spark plug hole on a 4.6L ford motor. I want to make sure the insert will never come back out and can withstand the heat. Thinking about using a green retaining ring compound with primer first instead of a high strength red thread locker but not sure.. Please let me know what you would recommend. Thanks Andy

    • Brandon Gearing says:

      Hi Andy, thanks for your question. In your application, the temperature is too high to use Loctite 620 (green) as it’s only rated to 232 C. We do offer Loctite 2620 (red) which is rated to 350 C and is high strength. You can use this with Loctite SF 7649 primer. That said, the amount of temperature this will see at the bond line has to be better defined. Please feel free to call us at 1-800-LOCTITE if you have any other questions.

  31. Aaron says:

    I have used red thread lock on my crankshaft pulley bolt on a mk1 golf gti, it uses a 12 sided spline bolt and has 66ft.lbs of torque on it and supposed to have 1/2 a turn extra but I forgot to do this 1/2 a turn I probably went just Unser like 1/8 a turn. It’s a stretch bolt, do you think it’ll stay on with red locktight ?

    • Brandon Gearing says:

      Hi Aaron, thanks for your question. Threadlockers do have strength whether they’re seated or unseated so there is a good chance if you got good coverage and full cure. That said, we can’t make a guarantee in this scenario. Feel free to all us at 1-800-LOCTITE if you have any other questions. – Brandon

  32. […] to the fastener by the installer during installation. Here is some basic info so about them.…threadlockers/ The stuff you see pre-applied to fasteners is indeed a thread locking material, but not […]

  33. BAPD says:


    Is there any way to check the loctite-220 applied surface ???.
    I just want to verify loctite-220 applied or not, since visually i can’t identify the loctite-220 applied surfaces
    Thank you.

  34. ken says:

    HI, my r/c airplanes are powered by 2 stroke gas engines 20cc to 62cc in size, the motors are mounted to a wood firewall using 5mm aluminum bolts that thread into a threaded aluminium standoff mount, sort a bolt into a blind hole application, lots of vibration and some heat from the engine . What do you recommend?

    • Daniel Wergeles says:

      Hi Ken, you can test our Loctite 222, make sure to put a couple drops into the hole as well as on the bolt.

  35. Charlie craig says:

    I have a small oil leak where the two aluminum halves
    Of an aircraft engine mate. It would be very expensive to tear the engine down to permanently fix the leak. Do yoy think that it could be stopped with Loctite and if so which would be the one to use. Thanks

    • Daniel Wergeles says:

      Hi Charlie, do the valves have thread? If not you can test our Loctite 680. If they do, then test our Loctite 277.

  36. […] Leave the axle seals alone. They're not prone to leaking. Make sure you ziptie your slave. I've had at least 2 blow on an install because they were not ziptied. Have a rear main seal on hand, but make sure its returnable because they're not cheap. Also, get some high temp grease that is appropriate to lube the input shaft, for the throw-out bearing. I personally had 2 stock clutches fail on me, due to torque. They both looked brand new, so I'm not a huge fan of the stock clutch. I went with ACT street disc. It is noisy though. If you go that route, it comes with brand new bolts that already have loctite. But you should still get some so you have it for the motor mount bolts. I've seen several OE flywheel bolts that I have seen have a green loctite on them. This explains the differences in strengths, and green is suppose to be medium to high. I think red might be overkill.…threadlockers/ […]

  37. Rich D says:

    I need to press an automotive ball joint into an axle but it needs extra hold because the part has been replace several times before and the press in hole has worn some. My plan is to add loctite and a set screw. Which product do u recommend for a press in part? Thanks!

    • Daniel Wergeles says:

      Hi Rich, Loctite retaining compounds are typically chosen for a particular range of dimensions. For example, press fit to about 0.005” difference between the diameters (slip fit) would use Loctite 609 (or the newer Loctite 603).
      Newer, stronger Loctite 648 is intended for slip fit parts up to 0.006” difference between the diameters. Loctite 680 is intended for looser fits, up to 0.015” difference between the diameters. Select the best option for the fit of your parts.

  38. […] The Difference Between Red, Blue, Green and Purple Threadlockers – Henkel Adhesive Technologies Blog Reply With Quote […]

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