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?

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