Threadlockers are a family of adhesives designed to enhance the performance of fasteners. Back in the day, before these substances were invented, you had to use washers and tighten the screws in well to keep the substrates assembled.
However, there were always the micro-vibrations, extra loading, temperature variation, and other stressors that wore out the fasteners. Eventually, causing them to become loose or to fail. The addition of thread lockers minimizes these destructive effects, hence increasing the strength and longevity of these structures.
So if you’re given a choice between two similar thread lockers, which one would you use? Here’s a detailed comparison of Loctite 242 vs. 243 to help you in selecting the right one.
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Loctite 242 Threadlocker - Blue Liquid 1.69oz Bottle | VIEW ON AMAZON |
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LOCTITE 243 Threadlocker for Automotive: Medium-Strength, Oil Tolerant,... | VIEW ON AMAZON |
An Overview of Loctite Threadlockers
This family of binding adhesives was developed in the labs of Trinity College in Hartford, Connecticut around 1953. Professor Vernon K. Krieble soon came up with the brand name Loctite, which remained in the family till 1997. That’s when the German giant Henkel acquired it.
There’s a hierarchy of thread lockers categorized according to their binding strength. And to make things easy for users, they have a color-code and a referencing number. Here’s an example of how it goes:
- Loctite Purple 221 and 222 are low strength thread lockers
- Loctite Blue 242 and 243 are medium strength thread lockers
- Loctite Red 262, 271, and 272 are high strength thread lockers
The most common type is the medium strength Blue. Its popularity is justified when you get to know its properties, and that’s exactly what we’ll do next.
The Similarities Between Loctite 242 and 243
Both thread lockers share several properties, which is to be expected. After all, Loctite 243 is an upgrade of Loctite 242. Here’s what they both share.
Strength
Medium strength thread lockers are suitable for assemblies requiring standard hand tools. They’re often required to be taken apart at intervals for routine maintenance and servicing.
While these adhesives are used, they dry up anaerobically sealing off the micro gaps between the threads and the bound surface. This adds the right amount of stress resistance, in addition to protection from corrosive agents.
Thread Size
The standard range for both is ¼ inch to ¾ inch threads. This covers a broad range of applications in automotive, light maintenance, and various domestic uses.
Curing Time
Both thread lockers take around 10 minutes to dry, and a full 24 hours to cure. These figures are more common for steel. It takes a bit longer on less-active metals.
If you need a solution that takes less time to function, you check out the Loctite QuickTape 249 Threadlocker.
In the cured form, both adhesives become a solvent-resistant, non-flammable solid, that’s also capable of wicking away moisture.
Removal with Regular Tools
This is among the fundamental features that make Blue thread lockers popular: you can remove them with simple tools.
To clean up Loctite 242 or 243, you can wipe it off with a clean cloth within 5 minutes of application. After that, you’d need a putty knife to take out the dried bulk. Follow that with soaking in methylene chloride and mechanical abrasion with a metal brush.
Temperature Range
The working temperature range for both Blue thread locker is -65 to 300 degrees. That’s why you could heat up a stubborn bolt to around 270 degrees to loosen it up a bit. Also, you can freeze the adhesive tube to extend its shelf life.
Packaging
Both thread lockers come in the same red bottle, which is what the brand uses to set itself apart from the competition. Namely from the Permatex products, as they offer almost identical adhesives. However, the liquid inside these red Loctite bottles is invariably blue.
The medium strength adhesive is available as a liquid, a tape, or a glue stick.
The Differences Between Loctite 242 and 243
There isn’t a host of differences between both adhesives, but the ones that come with the upgraded 243 are certainly worth noting.
Oil Tolerance
This is the main feature that sets the 243 from anything else. It can take a bit of oil contamination, without that affecting its mechanical properties in any way.
This opens up a new range of applications where the presence of oil is quite normal. And cleaning up all surfaces prior to applying the thread locker was a hassle. An extra step everyone is glad to dispose of.
Primer Requirement
This is also related to the previous point. That’s because part of preparing the surface for using a thread locker meant using a primer. This is no longer a requirement with the 243.
A primer also needs to be used while binding two inactive methods.
Typical Usage
Both products are great on regular threaded fasteners and have the same set of limitations. For example:
- They shouldn’t be used with plastic or thermoplastic materials.
- They shouldn’t be used within pure oxygen or oxygen-rich surroundings.
- They should be a sealant for chlorine or similar strong oxidizing agents.
- They aren’t food-safe grade adhesives
Having a few extra properties makes the usage of the 243 a bit different from the 242. Here are the typical uses for each.
Loctite Threadlocker 242
In automotive applications, it’s usual to use thread lockers in alternators, water pumps, and some types of valve covers.
Light machinery in general benefits from a regular thread locker, like tow motors and most domestic mechanical parts. Lawnmowers are particularly good applications to minimize the vibrations and noises they make.
Loctite Threadlocker 243
Oil pans are naturally top the list, together with disc brake calipers, pulley assemblies, rocker studs, and rocker adjustment bolts.
The previous applications mentioned for the 242 are just as eligible for the 243.
Conclusion
As always, practice safe procedures as you work with these adhesives. Avoid inhaling them, or letting them come in contact with your skin and eyes. Store the opened tubes in a cool dry place, and make sure they’re tightened well.
Finally, dispose of the used tube or materials in the proper manner outlined by the local authorities.
Both the Loctite 242 and Loctite 243 are quite common thread lockers, and you probably saw them in every workshop you’ve been to. And in plenty of households as well. The oil tolerance matter of the 243 is certainly a good feature. But if you don’t have a particular need for it, the 242 will serve you well.