Which Loctite do you use ?

[Brian JohnParticipant @brianjohn93961]

I was watching a Youtube video and the English narrator was using Loctite 542 for the steam chest grub screws.

I was just wondering : which Loctites do you have on your bench ? Is there one general purpose Loctite you always reach for ?

[Simon CollierParticipant @simoncollier74340]

620 for hot parts, 680 otherwise. Also the blue threadlock the number of which I can’t remember.

[JasonBModerator @jasonb]

Depends on what the Loctite is being used for.

 

The 542 you mention is a thread sealant so should be used for that. If you are retaining parts on a shaft then you want a retainer, I tend to use 648 for that. If you want to lock a thread in place then you want a thread locker and how easy it will be to undo will dictate which number you use and so on.

[DiogenesParticipant @diogenes]

Brian, I think people’s answers will mostly be relative to the work they usually do – I always have 638 (or similar ‘permanent’) on the bench because mostly I just want to bond parts together..

..but I don’t work with live steam, so additional properties of sealing at high temps and pressures are not necessary..

Also the blue (er, two-four-something?) threadlocker as above.

With ref. to a comment by @Simon Collier elsewhere, I do use 638 (sparingly and without full prep) to ‘glue’ parts together for spotting through – a thin smear lightly clamped ‘the night before’ usually holds fast enough for that operation without being a PITA to separate afterwards.

[Brian JohnParticipant @brianjohn93961]

I was mainly referring to Loctites use as a thread lock/sealant rather than as a ”glue”.

[SillyOldDufferModerator @sillyoldduffer]

Most of the time I use ordinary super-glue because it’s cheaper and available.   Not for everything though!  Superglue is for low temperature permanent joints.  Therefore, not good for fixing hot objects.   Though superglue works as a thread-locker, it’s risky:

• not a good choice if the fastener has to be undone later – it’s too strong.   Or
• too weak!  Ordinary superglue is weakened badly by oil, including cutting fluids, which are likely to be found on a thread.

For thread-locking I use Loctite Blue (243).  It’s deliberately only strong enough to stop loosening due to vibration, whilst being weak enough to break when undone with a hand-tool.   243 also tolerates oil, so it’s does what it says on the tin.

I often super-glue flat objects on to a mandrel, much as watchmakers use Shellac.  Shellac may be better because it can be broken by mild heat, but I don’t have any.   To get superglue apart I boil or oven bake the assembly, or long soak it in Acetone.   This is a bodge compared with choosing the best product available, like using a low temperature Loctite,

The various Loctites available are optimised to meet one of many different needs, such as:

• high or low temperatures.
• oil resistance
• strength of joint (use weak Loctite on threads, strong on joints)
• gap filling (ordinary looseness is not the same as a gasket)
• wicking into tight spaces
• gluing different materials, metals and non-metals
• fast or slow acting (tacking or not)
• and more…

I don’t worry about “which Loctite” because most of my needs are met by ordinary superglue and blue thread-locker.  Although my needs are basic, I’m aware a wide range of adhesives are available and what they do is explained on the Henkel website.  (Other brands available.)

One thing I learned early about glue was to follow the instructions.  Many glues demand absolute cleanliness and degrade rapidly once the package is opened.  If the joint matters, don’t fudge it!  Clean enthusiastically, and apply new glue, or older glue properly stored.

Dave

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, if you want a Loctite sealant, the best people to consult would be the people that produce it, e.g. Thread Sealing Solutions

Regards Nick.

[Brian John]

On Brian John Said:

I was mainly referring to Loctites use as a thread lock/sealant rather than as a ”glue”.

If it is for the type of pipe fittings that you mention in your other thread then the 542 will be a good choice and as you are working with fairly low steam pressures it should be OK with the heat. If you want something a bit more heat resistant then 554 would be better but not so easy flowing on fine threads as the 542.

I would steer clear of “superglue” as that is only good to around 80deg C

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, yes 554 may be better, but the price of it might empty your wallet, quite costly if you’re only going to need a small amount.

Regards Nick.

[JasonB]

On JasonB Said:

If it is for the type of pipe fittings that you mention in your other thread then the 542 will be a good choice and as you are working with fairly low steam pressures it should be OK with the heat. If you want something a bit more heat resistant then 554 would be better but not so easy flowing on fine threads as the 542.

I would steer clear of “superglue” as that is only good to around 80deg C

Used correctly “superglue” is marvellous stuff. As a temporary glue for metals it cannot be surpassed. Boiling water or a sharpn tap with a hammer will break the bond.

Otherwise go to the Loctite websites and read the literature very carefully. You will find want you NEED unlike looking at YouTube.

JA

The residue of “superglue” can be cleaned up with Acetone or a scraper.

[Brian JohnParticipant @brianjohn93961]

As Jason confirmed, 542 seems to be a good all-round choice for what I need so I will start with that.

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