A discursive look at Napoleonic & ECW wargaming, plus a load of old Hooptedoodle on this & that


Monday, 16 December 2013

Lead Rot - a Seasonal Revisit

Corroded solder tip, before cleaning up
Yesterday, the gales having calmed down a bit, my son and I got to work to put up the lights on our outside Christmas tree. We have a set procedure for getting this done - it's a fiddly job which involves falling off ladders and other festive traditions.

This year, we got off to a bad start. One of the two strings of lights wasn't working. Now I realise that this is also part of the true Christmas tradition, but we have had no problems of this sort for many years, so our procedure doesn't cover this too well. After messing around swapping individual bulbs - with no benefit - we eventually decided to make a proper job of it, removed all the bulbs and took them indoors, checking each one with a test meter. In fact they were all working, but the solder around the tips of some was showing some deterioration - a pale grey, crystalline deposit which made it tricky to make a decent contact with the test meter.

So I gave them a quick going over with a file - it took less than 15 minutes to clean up 40 bulbs - we screwed them firmly back into their sockets, checked the fuse and the complete circuit with the meter, connected them up, and voila! - Hark, the Herald Angels Sing.

Nick was impressed that our botched repair had worked - though probably less surprised than I was. We got on with the job we had set out to do, and got everything up and working.

So - what is this stuff? The Christmas lights spend Christmas hanging on a tree, obviously, in all sorts of weather conditions, none of which are oppressively warm. The rest of the year they live in a plastic tub in the garage, which can get very cold, though it is protected from direct frost and snow. The crystalline salt, whatever it is, will rub off, but it doesn't conduct very well, and - the main point here - I would not like my toy soldiers to turn into grey dust.

All right, you metallurgists and chemists - should we worry about this sort of thing, or will I be all right if I just don't hang my soldiers on trees or keep them in the garage?

5 comments:

  1. When you take them down try washing (wiping?) the tips with a solution of white vinegar, and then rinsing and drying them. Vinegar (white) is the cure for lead-rot....there's a very detailed (and somewhat complicated 'instruction') in one of the Toy-soldier books but I can't place it, that involves boiling and all sorts, obviously you can't start boiling bulbs, but equally you don't want to be leaving strong solutions of vinegar in the tips, but as they are smooth, three cloths should do the trick - vinegar - damp rinse - dry?

    Might help...might kill them all!
    H

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  2. With respect Maverick, Acetic acid appears to be the cause not the solution (or the precipitate).

    A timely reminder to look through your lead pile for plague carriers.

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  3. Thank you both, gentlemen. To amuse myself, I had a read through some threads on TMP on this subject, and I've never read such a lot of superstitious old wive's tales in my life - almost complete crap. Vinegar is interesting - it will react with lead to produce a coating of lead acetate, which has occasionally been suggested as a good thing. Maybe it is, but the lead content in modern castings is low - the instability problem at low temperatures is to do with the deterioration of tin in cold conditions - what i believe is called tin pest. This is alleged to have caused problems for Napoleon's troops in Russia, when the pewter buttons on their gaiters fell to bits, and they got problems with wet feet and frostbite. It was also a problem for Capt Scott and his merry men in the Antarctic, when the cold destroyed the solder seals in their jerry cans of cooking and fuel oil, and the oil ran away - which did them no good at all.

    Thus my reference to Lead Rot is inaccurate, as I suspect it has been in parts of the TMP threads as well - the problem ingredient in lead-tin alloys at low temperature is the tin - which I think is also probably corroded by acetic acid. Apologies - untidy thinking on my part - the deterioration of lead-tin alloys in cold weather is due to the tin breaking up through tin pest; damage to the lead content because of chemical action is a separate problem (which should be limited in scope in modern alloys), but vinegar would tend to accelerate it.

    Hmmm.

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  4. The acetic acid thing is why you DO need to rinse, but it also stops the rot so-to-speak. It's not to be left on, it's about fighting fire with fire as it were. Perhaps that's where the boiling came in? Or maybe you had to rinse with distilled water!! I've successfully treated flats that had a high lead content and were nearly 100 years old.

    As Mr Foy has discovered there is a lot said about it, as there is about scale/size/ratio (particularly the eponymous HO/OO of dear old Airfix!), plastic rot, Nazi party uniforms, SS re-enactors and anything else that allows people to sound knowledgeable while upsetting other members of the forum!

    While gaming figures have had the lead drastically reduced, I suspect the bulbs will be softer (more lead content) as there is an airtight element to the invention of / necessity for; a seal?

    But it was only a suggestion!
    Hugh

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    Replies
    1. Hugh - you're right - the solder on electric bulbs is unlikely to be fine pewter, right enough - there is a whole range of alloys here - and your old flats will certainly be high lead. What happens to lead sheeting on roofs, by the way? It changes colour, but then it can last for decades - it might not if it rained vinegar, though…

      My immediate problem is solved by having physically cleaned up the solder areas - if it gets worse again I can repeat the job, or try the vinegar. It would be stupid of me to associate what happens to my light bulbs with bug-a-boo tales of disintegrating white metal castings, but I have heard (from Featherstone or someone), long ago, that figures should not be allowed to freeze.

      Where else could you get fun like this?

      Delete

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