|Corroded solder tip, before cleaning up|
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?