Friday, 21 January 2011

Polymerisation / Procrastination

So, I had a few boring little online chores to do this afternoon - setting up bill payments, checking postal addresses... boring boring boring
Therefore, obviously, as soon as I sat down with my laptop I was filled with a sudden urge to know about the white residue from superglue that I mentioned in my last post. Having  managed to not think about this for three weeks, suddenly the research could be put off no longer for I would die if I did not find out.
Never let it be said I don't procrastinate properly

Turns out it's quite simple really: Superglue gives off vapours as it sets, these vapours react in the presence of moisture to make white crystals. These white crystals are the residue.
But, well, it's me. I want to know the real science*. Come along for the ride:
Superglue is basically ethyl cyanoacrylate (ECA). Cyanacrylate glues work because they polymerise in the presence of very small amounts of water (the water is a catalyst. It doesn't join in, but it encourages the  esters to go play) - such as water vapour in the atmosphere. When they polymerise, they solidify, and form long strongly bonded chains, binding your surfaces together.
However, this polymerisation is an exothermic reaction - it gives off heat into the surrounding atmosphere. Being heated causes small amounts of the cyanoacrylate to vaporise. In the open air, that's fine, because the vaporised molecules just disperse and your craft projects will be safe. But if you pack away your project to soon after gluing it together, the molecules are effectively trapped. As they cool they too will react if there is any moisture around (such as in fingerprints on your project), polymerise and solidify into white crystals - seen as the white residue ruining your project.
According to CSI this method can also be used to pick up fingerprints at a crime scene, though personally I can't help but think there must be easier ways... like with talcum powder...

Anywho - with regards to craft projects, clearly prevention is better than cure, and you're best to leave your project out for a few hours / overnight before you tidy it away to make sure the glue has fully gone off (cyanoacrylates set solid in a few seconds, but the  reaction takes a few hours to fully complete).
You can remove the residue with acetone (nail varnish remover) but obviously that may well bugger up the finish on your project too. If you're careful you can scrape off the residue with a  blunt object - like a fingernail or lollipop stick - but it's an imprecise art

Still, you can take solace in knowing exactly what the stuff is. Hurrah.
Nerdy Noodle xxx

*For purposes of clarification - I have had to guess at a bit of the science. It seems the craft nerds out there don't care why the residue happens, and the science nerds don't care about superglue in this level of detail. From what I can glean, with my limited science knowledge, this is what happens. It may all be completely wrong.

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