A frank, open, and honest discussion of threadlocking products.

Big Bad

Big Bad

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Experiences with invisibly loosening bolts and machine screws, in the case of this post those found on firearms, especially scope mounts, has made me a religious user of threadlockers, liquid or gel products that you apply to the threads of a bolt before tightening and which will ensure it does not loosen due to vibration or other trauma. And for sure, I do not want to be losing parts out in the field or tightening and retightening my scope mount screws, changing the point of impact.

There are two main manufacturers of such products, Locktite and Permatex and I'm going to try to post info from each. Personally, information about the recommended use of the various versions of threadlockers, the main versions of which are red and blue but with many variations, has always been hard to find so I'm going to try to search out what I can from the makers and various users.

I'm starting with Loctite products, as described via the link at the bottom:



Mechanical locking devices (such as split ring washers, nylon insert nuts, and serrated tooth washers were invented to solve the common problem of loosening that happens in most threaded assemblies). However, the reality is that they don’t “lock” the assemblies and can’t maintain clamp load. These devices often loosen under vibration, thermal expansion, bending, and/or improper torque.

Threadlockers, or threadlocking adhesives, are the solution to this problem. Applied between two mating threads, these liquid threadlocker adhesives secure nuts, bolts, and threaded fasteners in place. They cure to form a strong bond that prevents loosening, ensuring assemblies retain clamp load over time.

Threaded fasteners, such as bolts and nuts, have a huge role to play in many industries. Their impressive clamp load means they are the ideal fastener for use across a wide range of manufacturing and maintenance applications. However, these types of assemblies can fail over time as they work themselves loose, thanks to vibration, bending, or thermal expansion.

Choose from a range of different strengths and application types and discover LOCTITE® threadlockers that:

Reduce downtime
Provide strong, long-lasting adhesive performance
Reduce the risk of loosening and leaks
Lower maintenance and manufacturing costs

Contact a member of our team today to find out more about our LOCTITE® threadlocker solutions.

To find out more about our LOCTITE® services and support, you can request a free LOCTITE® Consultation.

Benefits of LOCTITE® Threadlockers

LOCTITE® threadlockers are products you can trust for securing threaded fasteners in place. An industry-leading solution for more than half a century, they offer versatility, affordability, and reliability in your assemblies.

Threadlocking compounds can effectively reduce the impact of costly failures, repairs, maintenance, and downtime. Applied to one or two threads before assembly, LOCTITE® threadlockers push the air between the threads out as the fastener is tightened. The anaerobic threadlocker material cures in the absence of air to form a strong, thermoset plastic that locks threads and joints in place.

LOCTITE® threadlockers can also lower the effect of corrosion in threaded components and help to prevent leaks in your assemblies. Applicable across both maintenance, repair, and operations (MRO) and original equipment manufacturing (OEM), LOCTITE® threadlockers improve reliability, eliminate failure, and boost productivity in your operations.

Our threadlockers are single-component liquid adhesives that secure nuts, bolts, and threaded fasteners. They are designed to eliminate air gaps that, combined with vibration and shock, that allow for loosening in threads. This is achieved by forming a strong bond between the threads that holds everything tightly in place with a controlled strength thread lock.

All LOCTITE® threadlockers have a broad temperature resistance of -65°F to 300°F, while some threadlockers are designed for high temperatures up to 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.

Choosing a LOCTITE® Threadlocker

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 range of household repairs. These different grades or thread lock types are color-coded to help you distinguish one threadlocker type from another. Our user guide contains a threadlocker chart that details the properties of each product. 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.

Choosing between a LOCTITE® red, blue, green, or purple threadlocker will depend on the specific needs of your project and the threadlocker strength you require. To find the right threadlocker for your task, key considerations should include:

Maintenance and disassembly needs
Temperature requirements of application
Application strength and vibration levels
Type of assembly
Thread size
Application area and location

Differences between Threadlocker Grades

LOCTITE® Red Threadlocker

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

LOCTITE 263
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LOCTITE® Blue Threadlocker

LOCTITE® blue threadlocker is medium strength threadlocker adhesive. This product cures fully in 24 hours and can be disassembled with hand tools. Blue threadlockers are removable with standard hand tools on 6mm to 20mm fasteners, have fast fixture times, and are available in liquid, stick, paste and gel form. Moreover, there is also LOCTITE® QuickTape 249™ Threadlocker, the one and only of its kind globally. A primerless grade blue threadlocker is available as well.


LOCTITE 243
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LOCTITE® Green Threadlocker

LOCTITE® green threadlocker is recommended for locking preassembled fasteners, e.g. electrical connectors and set screws, and prevents against loosening, rust, and corrosion. This wicking grade threadlocker is categorized as a medium-to-high-strength adhesive. Also available in a liquid form, LOCTITE® green wicking threadlocker cures in 24 hours and can be removed with hand tools and, in rare instances, may require heat to assist when threads have excessive engagement lengths.


LOCTITE 294
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LOCTITE® Purple Threadlocker

LOCTITE® purple threadlocker, also known as LOCTITE® 222™, has become one of our most successful products. LOCTITE® 222™ cures in 24 hours. This low strength threadlocker can be used on metals such as aluminum and brass and offers a lot of flexibility to the user.

LOCTITE® purple threadlocker has many uses, from carburetor screws to eyeglasses to small screws on laptops. Due to the threadlocker being low strength, it can be removed with the same tool used to put the project together. It is available in an easy-to-use liquid application, which makes the product especially efficient with very small screw applications, less than ¼ inches in diameter.

LOCTITE 222
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Compare Featured LOCTITE® Threadlockers

Find a solution for your application, from a permanent threadlocker for strong, long-lasting bonds in OEM applications, to removable products that allow for effective MRO strategies, with the range of LOCTITE® threadlockers:


https://www.henkel-adhesives.com/us/en/products/industrial-adhesives/threadlockers.html
 
Hey Big Bad thanks for posting. I recently switched from using Loctite 242 to 243 after reviewing a "Technical Tuesday" video from Shadow Systems. Here is a quick cut and paste ..........Loctite 243 comes with significantly improved oil tolerance. Even if your threads are a little dirty and oily, it’s not a big deal. No need to use any primers on plated fasteners either.
 
Permatex products are a bit harder to find out much about; this is the best site I've come up with so far. It's darn near impossible to make a repost of it un-confusing but the link is there. I do note the bit about Loctite 243, my oil resistant favourite blue version for guns and which is inobtainium right now, at least where I live. Also, not mentioned here but there is a new Permatex orange sealant which is said to be the best all round between red and blue:


Permatex vs Loctite: Threadlockers & Sealants

This site contains affiliate links to products. We may receive a commission for purchases made through these links.

I’ve seen so many people get confused about Permatex and Loctite, that I finally decided to do a comprehensive post on these two.

Today we’ll be looking at both brands’ threadlockers and thread sealants. Common identical products here are:

Loctite 565 vs Permatex 56521 for thread sealants

Loctite 242 vs Permatex 24200 for threadlockers (medium strength)
Loctite 515 (or 518) vs Permatex 5183 for anaerobic flange sealants

Did you notice something in their numbers? Yep, they’re made like this for easier cross-reference.


Let’s take a look at the differences between them – if any at all in some cases

A little trivia: Loctite bought Permatex in 1972, and around 2000 they sold them back. Currently, Permatex’s owner is Illinois Tool Works – the same company that owns Hobart and Miller welders, Tapcon fasteners and many more.

Loctite 243
Best medium strength threadlocker. Oil resistant and holds things tighter. Improvement over 242 and Permatex 24200.

CHECK PRICE ON AMAZON
SPOTLIGHT
Loctite 565

Loctite 565
Loctite’s most widely used thread sealant. Withstands pressure, temperature and prevents leaks.

CHECK PRICES
SPOTLIGHT


Permatex 56521
Absolutely the same as Loctite’s rival product. I guess get it if you prefer blue over red letters, as it’s as powerful and useful.

CHECK PRICES
SPOTLIGHT
Gasket

Permatex 51813
Fills bigger gaps which can be important in some cases. Otherwise has the same function and properties as Loctite 515/518.

CHECK PRICES

Permatex vs Loctite:

Threadlockers

The threadlocker products from both brands are almost the same. By ‘almost’ I mean that with general use, you won’t notice any significant difference.

There are, however, two small details.

First, Permatex has gel twist type threadlockers like the 24010.

Permatex Gel

It’s essentially the same product like the Permatex 24200 and Loctite 242. However, it introduces two improvements:

Supports bigger fasteners: 1/4″ to 1″ instead of the usual 1/4″ to 3/4″.

The gel is easier to apply – especially with vertical applications.

Second, Permatex is a bit slower in terms of fixture time. It will set in at around the 20-minute mark while Loctite 242 does the same after 15 minutes. Both fully cure after 24 hours.

Note: If you want a medium strength threadlocker and don’t care about gels, check out Loctite 243. It’s an improved version of both 242 and 24200 – primerless and oil resistant.

Keeps fasteners even tighter, and doesn’t require you to do a thorough cleaning on the threads beforehand.

SPOTLIGHT
243 TAB

Loctite 243

Best medium strength threadlocker. Oil resistant and holds things tighter. Improvement over 242 and Permatex 24200.

CHECK PRICE ON AMAZON
But really, there isn’t much difference between the whole lineup of Permatex or Loctite threadlockers. They even share the same color scheme for the strength/hold of their threadlockers:

Purple for low strength

Blue for medium strength

Red for high (permanent) strength

The blue threadlockers will be OK for 90% of your projects. If you need more info on Loctite’s products, I’ve compared their threadlockers already.


You can check the Permatex 24200 and read what people say about it. Still, as I said, I recommend Loctite 243 over any other medium strength product.

Thread sealants:

Permatex 565221 vs Loctite 565

Two favorites of plumbers and mechanics – but not only. You’d need these two for a variety of pipe/fitting sealing jobs from waste treatment, to hydraulic lines, to brake fittings, air conditioners…

I’ll be frank: they’re literally the same thing.

Both work with any NPT (National Pipe Thread) that’s up to 2″ – that’s 5cm for those using the metric system.


Also, both withstand pressure of up to 10,000 psi.

Surprise, surprise – both of them also have a temperature range of -65°F to 300°F.

I mean, if you have any specific brand preference, go ahead and buy whichever you feel better about. Even the tubes have the same design.

The important thing is that you won’t have any leakages and will benefit from your benefits not rusting/corroding after you use either of them.


SPOTLIGHT
Loctite 565

Loctite 565
Loctite’s most widely used thread sealant. Withstands pressure, temperature and prevents leaks.

CHECK PRICES
SPOTLIGHT


Permatex 56521
Absolutely the same as Loctite’s rival product. I guess get it if you prefer blue over red letters, as it’s as powerful and useful.


https://toolingfun.com/permatex-vs-loctite-threadlocker-sealants/
 
Standardvel said:
When in a bind I have used nail polish, it comes in many colours.
Click to expand...

It's better than nothing for sure, but in my original scope trauma I had a .22 scope slip out of its mounts and hit the floor, fortunately onto a carpet, after a minor thump when I put the rifle down to return it to its safe. When I'd mounted the scope 10 or maybe even 20 years earlier, I didn't have any Loctite and so I used red nail polish. The fact that it was still visible at the base of the screws gave me a false sense of security I guess, even when the rifle went inaccurate at the range in the weeks before. I was a threadlocker believer before that, but after The Incident I became a fanatic about it.
 
If you use any thread locking liquid on any part of a firearm you should not be allowed to own a firearm.
40 yrs experience as gunsmith Remington, Winchester browning and other companies warranty smith built custom rifles from blue printing actions and so on .
Not sure about anyone else’s qualifications other than the internet .
Degrease all screws and holes other than that a non issue .
Maybe the screw on a mossberg 500 safety .
Just saying carry on with the comments
 
My friend just has a Ziess scope that he sent in for warranty work. Ziess asked him if thread locker was used on the ring screws. He said yes and warranty was denied. Scope was returned damaged to him (rings had been over tightened and damaged internals). This happened like a month ago.

Edit: I should add they are Ziess rings and were torqued to spec.
 
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I have seen enough mount bases come loose over the past 5 decades.
Another one is guard screws, particularly on certain platforms.
Loctite gets the nod on those applications. Either blue or purple. Dave.
 
struff55 said:
If you use any thread locking liquid on any part of a firearm you should not be allowed to own a firearm.
40 yrs experience as gunsmith Remington, Winchester browning and other companies warranty smith built custom rifles from blue printing actions and so on .
Not sure about anyone else’s qualifications other than the internet .
Degrease all screws and holes other than that a non issue .
Maybe the screw on a mossberg 500 safety .
Just saying carry on with the comments
Click to expand...

Well that is definitely an opinion and thanks for sharing it. Seems a little harsh though.
 
Worth looking into Vibra-Tite VC3. You apply it to the fastener and dries in open air. Also reusable up to 5 times (assemble-reassemble). Same kind of stuff as what comes on Magpul Mlok bolts.

Just began using it, so no long term review just yet, but feels solid so far.
 
Standardvel said:
When in a bind I have used nail polish, it comes in many colours.
Click to expand...

yup.... i have a little bottle of Sally Hansen's Hard as Nails in my fishin bag for quick repairs of flies and chipped jigs or lures and I have one in my hunting pack for using in place of loctite.
Can start a fire with it, seal a small to medium sized wound with it hehehe..... good stuff to have around.
 
Don't see Loctite 380 on here ,A GUN builder who is pushing 85 uses it best ever he says ,MY .02 WORTH
 
struff55;18997148 Degrease all screws and holes other than that a non issue . Maybe the screw on a mossberg 500 safety . Just saying carry on with the comments[/QUOTE said:
Bingo on degreasing all screws & holes to ensure proper torque values on fasteners. I wouldn't let Loctite touch any parts made from hard polymer plastics
like the Mossy 500 safety though as the stuff can break down many of today's plastics and cause them to crack & fail. (A metal safety button from a
Mossy 590 A1 is the way to go with Loctite.) ;)

I only use a wee dab of Loctite 243 on scope mount base & ring screws, but I apply the stuff only to the last couple threads at the top end of the screws where they go into the holes before final tightening. No issues fer me ever.
Click to expand...
 
struff55 said:
If you use any thread locking liquid on any part of a firearm you should not be allowed to own a firearm.
40 yrs experience as gunsmith Remington, Winchester browning and other companies warranty smith built custom rifles from blue printing actions and so on .
Not sure about anyone else’s qualifications other than the internet .
Degrease all screws and holes other than that a non issue .
Maybe the screw on a mossberg 500 safety .
Just saying carry on with the comments
Click to expand...

then you should also be familiar with the gentle and small aplication of heat needed to loosen thread locking glues .
 
SHELL SHUCKER said:
Bingo on degreasing all screws & holes to ensure proper torque values on fasteners. I wouldn't let Loctite touch any parts made from hard polymer plastics
like the Mossy 500 safety though as the stuff can break down many of today's plastics and cause them to crack & fail. (A metal safety button from a
Mossy 590 A1 is the way to go with Loctite.) ;)

I only use a wee dab of Loctite 243 on scope mount base & ring screws, but I apply the stuff only to the last couple threads at the top end of the screws where they go into the holes before final tightening. No issues fer me ever.
Click to expand...

It's definitely not recommended for plastic fittings. Warnings in big capital letters.
 
Raton57 said:
if your old enough to remember all the gun guys used iodine one mount screws and such. I have mounts been tight since the 70s still.
Click to expand...

Iodine as in the liquid you put on cuts? I used to use iodine to purify drinking water, the pure crystals in a glass bottle, and the vapours off of it, even with the cap on tight, would corrode metal like crazy. I have to think what they were doing secured the screws via 'microcorrosion.'


burnt_servo said:
then you should also be familiar with the gentle and small aplication of heat needed to loosen thread locking glues .
Click to expand...

That's only with red I think, the other colours exist because they can be broken with light force, meaning the screw can be removed normally. They don't glue parts together, they just prevent threaded metal from loosening from vibration or repeated shocks, like with the normal use of a firearm.
 
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