Every industry has a "thing", I'm sure of it. One of those pieces of lore passed on from generation unto generation about The Way Things Are Done. Often there's a good reason behind The Way, but equally often, nobody in living memory has ever witnessed that good reason in action. Probably because everyone follows The Way Things Are Done and so doesn't have to re-visit the pain of why doing it a different way is wrong.
In my industry, of ultra-high vacuum engineering, that thing is brass. Brass, for the non-metallurgically wise, is an alloy of copper and zinc, and "everyone" knows that you must never, ever use brass in an ultra-high vacuum system. Weird things happen. Namely, the zinc migrates out of the alloy and evaporates, leaving copper behind, and coating everything inside your vacuum system with a very thin coating of zinc oxide. At this point, I shall simply assure you that a thin coating of zinc oxide is a Very Bad Thing.
I have worked on ultra-high vacuum systems for twenty-two years, and I have never seen this happen. My colleagues have, between them, some 180-odd years of experience in ultra-high vacuum system. None of them has ever seen this happen. Obviously, we've all been good and avoided putting brass components in our systems.
I have spent the past couple of weeks banging my head against a brick wall of intransigent scientific instrument, at the heart of which is an ultra-high vacuum chamber. Nothing about it made sense, and eventually, in a cascade of exploding electronics, it finally gave up functioning completely last Friday afternoon. So yesterday I pulled it apart, and found a curious grey deposit all over sections of it. Usually when we find Nasty Things, they turn out to be hydrocarbons, and can be dissolved in alcohol or hexane. This stuff didn't want to dissolve that way.
We all stared, poked and prodded the contaminated surfaces. It was like nothing we'd seen before, and it was everywhere. Normally, we consider a faint smudge or spec of dust to be contamination. Things that are not visible to the eye can be bad enough to stop our instruments working properly. We handle everything with surgical gloves. None of us were prepared for this level of crap. My son comes home from school looking cleaner than this thing.
We looked forlornly at each other, at the floor, and at the ceiling, hoping for inspiration. We drank cups of tea. And then I looked more closely. And I noticed something odd about some of the connectors right in the heart of the machine. Little gold-coloured connectors, that were no longer gold-coloured, but a beautiful salmon-pink. Almost as though they were now made of copper.
(With the benefit of hindsight, and my little mention of brass, I'm hoping you can all see where this is going...)
A spot of hunting around, measuring, comparing, and a growing sense of horror, I realised that the connectors had been taken from the wrong packet. They were brass, and supposed only ever to be used in building electronics, and never in a vacuum system. And still my colleagues couldn't quite believe that such a tiny connector could create so much stuff everywhere. Still, there were dissenting voices asserting it must, somehow, be copper oxide, or iron oxide that we were seeing, and not zinc oxide. So out came The Rubber Bible and we were able to determine that there was a simple test - if our gunk dissolved in sodium hydroxide, it was zinc oxide, and if it didn't it was copper oxide or iron oxide.*
Friends, the oxide dissolved in sodium hydroxide.
We actually managed to do that thing that everyone knows you shouldn't do. We evaporated zinc out of brass to leave pure copper, and coated every internal part of a beautiful mass spectrometer with zine oxide. (A beautiful mass spectrometer that was supposed to be winging its way to its customer at the end of next week, which is a teensy weensy issue now). But the thing is, despite the fact that it's all totally buggered, I'm so much happier than I've been in weeks, because I know why it's buggered. I have found a simple, elegant explanation for every problem this machine has had. I have used a simple, elegant chemical test that demonstrated that my hypothesis was correct. And I got to use The Rubber Bible.
Today, I scienced. And it was good.
* This would get very long and tedious if I went into all the details of why we knew it was an oxide, and why it was limited to those three materials. You're just going to have to believe me.
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