Softening epoxy

[John HaineParticipant @johnhaine32865]

I have a small brass block with holes into which some LEDs are fixed using epoxy.  The LEDs are 30 odd years old and have been running continuously so their light output is poor, so they need replacing. The glue is probably Araldite judging by its colour. I’m going to try putting the item in a jar of acetone and leaving it for a few days as I have seen this recommended. Other ideas welcome!

[Michael GilliganParticipant @michaelgilligan61133]

The encapsulation material of the LEDs will probably dissolve before the Araldite … but I guess that’s not important.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

As an alternative, I would suggest thermal shock

i.e.  embrittlement rather than softening.

Liquid Nitrogen ?

MichaelG.

[Andrew TinsleyParticipant @andrewtinsley63637]

Yes the liquid nitrogen trick works. But don’t have access now I am retired.

Andrew.

[Roderick JenkinsParticipant @roderickjenkins93242]

Half a century ago I removed stainless steel mesh epoxied to aluminium screen printing frames using a proprietary liquid that smelled strongly of oil of wintergreen, which I believe is mostly  methyl salicylate.  I wouldn’t be suprised if it also included methylene chloride which is generally banned for domestic use. So, that’s not much help.  There do appear to be plenty of proprietary solutions available though.

Rod

[MacolmParticipant @macolm]

There are chemical “solvents” that disintegrate most epoxies. One brand I remember is Ardrox which seems to be still available. The product we used had a quantity of oil that floating on top; you shook the can and poured out what you needed, then lowered the item through the oil to hang in the noxious brew. It was quite slow acting, but did not attack metals and most plastics.

[John HaineParticipant @johnhaine32865]

I guess the best thermal shock I can do is freezer to boiling water, or maybe hot cooking oil to ice bath.  The electronic components need replacing anyway so it doesn’t matter if they get destroyed in the process.  Rod you mentioned “proprietary solutions”, please could you point me to one?  Also not obvious what Ardrox product to use, they have a wide range and their website doesn’t mention “epoxy”.

[Michael GilliganParticipant @michaelgilligan61133]

John

At that vintage, there’s a good chance that the Araldite was ‘2002’ or something similar … so you might find this of relevance:

http://silverbiplanes.com/SPECIFICATION_PDFS/British_DTD/DTD_900A_1988.pdf

Sorry, don’t have time to dig any deeper today.

MichaelG.

[Kiwi BlokeParticipant @kiwibloke62605]

Alternative ‘thermal shock’ – heat! Either the epoxy or the LED encapsulant will give up at domestic oven temps…

[Dick HParticipant @dickh]

Google “epoxy” and “pineapple juice”.

[Robert Atkinson 2Participant @robertatkinson2]

Methylene chloride is a good choice but as noted is now generally banned particuarly as paint stripper. However you can buy small quantities as solvent for welding plastics. I use EMA Plastic Weld.
As the LEDs are not being re-used you could also use mechanical methods.

Robert.

[John Haine]

On John Haine Said:

  Rod you mentioned “proprietary solutions”, please could you point me to one?  Also not obvious what Ardrox product to use, they have a wide range and their website doesn’t mention “epoxy”.

John,

I did a quick web search to see if I could find something that would help me recall the name of the product that I used to use.  There were plenty of options but none that triggered my memory. I’m afraid I don’t have any experience of the modern preparations.

Rod

[andy198712Participant @andy198712]

Ardrox 204 I think it is. Is yellow and thick, it’s DCM paint stripper and melts away a lot of stuff not just paint, at work we use it to melt structural adhesive. Worth a google but to be honest the easiest method I would think to try first is heat.
what’s the rest of the part like? Can you apply much heat?

[martin haysomParticipant @martinhaysom48469]

heat , use a hot air gun as it can be a bit stinky

[Russell EberhardtParticipant @russelleberhardt48058]

This might help:

https://www.loctiteproducts.com/ideas/fix-stuff/remove-epoxy-use-these-tools-follow-these-steps.html

Russell

 

[John HaineParticipant @johnhaine32865]

Thanks for all the suggestions.  I’ve now immersed the item in a jar of acetone and will leave it for a few days to see what happens.  Failing that I’ll pop it in the oven…

[Speedy Builder5Participant @speedybuilder5]

Drill them out ?

[John HaineParticipant @johnhaine32865]

I can risk damage to the block so drilling a last resort.  The Ardrox stuff is available in 25 litre quantity so expensive if it didn’t work!

Thanks for that link Russell.  A bit ambiguous, but they mention acetone so let’s see how that gets on.

I’ll report back when I have more information!

[John Haine]

On John Haine Said:

… maybe hot cooking oil to ice bath.  …

A freezing mixture of ice and salt would get the temperature a lot lower, if the presence of salt wouldn’t be a problem (maybe cling wrap?).  Or there are the freezer sprays you can buy.

George

[martin haysom]

On martin haysom Said:

heat , use a hot air gun as it can be a bit stinky

I’ve used this method several times, it works well.

[vintagengineerParticipant @vintagengineer]

MEK destroys most things.

[John HaineParticipant @johnhaine32865]

Thanks – any idea where MEK can be bought?

[Robert Atkinson 2Participant @robertatkinson2]

The Ardrox 204 is mainly methylene chloride so may as well use the plastic weld. If you can seal it in a metal or glass container to limit evaporation when soaking. Additionally they should not supply Ardrox 204 to private users. MEK does not effect epoxy much in my experience.

Robert.

[duncan webster 1Participant @duncanwebster1]

The stuff used to glue plasticard, mek-pac, is still available. No idea whether it affects araldite

[John Haine]

On John Haine Said:

Thanks – any idea where MEK can be bought?

After a really hard think I came up with a sensational idea – try E-Bay.

£8.99

https://www.ebay.co.uk/itm/272038690495?_skw=methyl+ethyl+ketone&epid=1950877697&itmmeta=01K36W4W1XYN8ZWS2PF2Y4HS1C&hash=item3f56c4febf:g:ngkAAOSwyV5ir4QS&itmprp=enc%3AAQAKAAAA0FkggFvd1GGDu0w3yXCmi1cr4kzuVIGxVhUten%2BMMu38jeviua1R%2BL8elXQUvKt86cJ72LNCj8BpQHXmVGlHxJOfouwoVMvQ4yb3qhFcnhmVnzaX49k%2FpHS05sPvfCfdxZ%2BBwYa%2FZ5qQrFo%2FnacccMDux81A43XVZIA%2BqllRb55WlNKgdsy7Xibt%2BIuODPmGza0YuNdjhV07hAAAWEwgo5hqiQAZqIusOvAVW%2FUtprlPed0Xfa7vssVCvPdRlT8V6DsyWpbqA9T44%2FwYRDAuNPs%3D%7Ctkp%3ABk9SR6TBk9yZZg

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