Hmmm, perhaps it would be more appropriate to say that I am now the proud owner of a pair of radioactive marbles…
It’s a funny old world when you come to think about it. A few weeks ago I penned a blog Is that a Geiger counter in your pocket or are you just pleased to see me? (Click Here to see that column.) In my musings I mentioned that I live just down the road from a nuclear power plant. Also, that with everything that’s going on in Japan, it might be a good idea to own a Geiger counter.
Well, someone suggested a cheap-and-cheerful do-it-yourself kit, which I duly sent off for and constructed. But when I powered it up … nothing happened as I discussed in a follow-up blog My Geiger counter doesn’t count! (Click Here to see that column.)
In that follow-up column, I mentioned that one potential problem was the fact that I didn’t have a radioactive source with which to test my counter – so as far as I knew (at that time) it might be working perfectly. Since then, of course, I’ve discovered that there is a problem because the LED is always on (it should only flash when a radiation event occurs) and I should be seeing a few flashes and hearing a few clicks every minute caused by background radiation.
Eventually I ended up sending my kit to David Ashton in Australia, because he is a master when it comes to fixing things that don’t work. By some strange quirk of fate, however, shortly after I’d returned from the post office, I received an email from Nick Bricteux (www.xtor.us) saying that he had just posted two uranium glass marbles to me – they arrived on my desk a few moments ago as I pen these words:
So, as I say, it’s a funny old world, because last week I had a Geiger counter but no source of radioactivity, and now I have a pair or radioactive marbles but no Geiger counter. Is it just me, or does everyone have problems like this?
Of course the fun thing is that I am now the only person I know – apart from Nick – who owns a pair of radioactive marbles (Nick assures me that they are only mildly radioactive – together they should be about 4 to 10 times higher than background radiation). Apart from anything else, this will give me some bragging rights here in the office and at family parties and suchlike (“What Shayne, you don’t own any radioactive marbles?
Nick also provided some additional information as follows:
Uranium glass (also called Vaseline glass – yellowish-green to dark-yellow depending on lighting and uranium content) was well known in the US before the war, but when the potential of uranium was realized during the war the metal was requisitioned for the war effort like copper and chrome (the very few new cars of that time came with black bumpers, headlights rings, trims, etc.. They were called "Black Special Edition" or the like). American cars in the 40's without any chrome, that makes you think...
Uranium glass had two main uses: one like any glass for dinnerware, ashtrays, drinking glasses and what have you. Its appeal was mainly its color. The other, more interesting use, was to make glass tubing out of it to use in "neon" signs (even though there was none in those devices). Due to its bright yellowish green fluorescence, you could make bright signs in the color where the eye is the most sensitive (~555nm wavelength). Just fill the tube with some argon gas at the right pressure and add some mercury to generate truckloads of UV radiation and there you go. The glass itself (like most glass) is mostly opaque to the UV anyway. That was a nice setup. It was also a lot less involved and less "tricky" than using phosphors (like it's done now) also the phosphors would degrade while the uranium glass wouldn't.
When the ban on commercial use of uranium took effect, the mood (war time) was not really about making "neon" signs anyway and a few places had such a glass in stock. After the war... began the cold war and not many people wanted to sell uranium-based products; the law was vague, patriotism and confusion were high, demand was low, and that part of the industry pretty much vanished (in the US anyway).
Some countries in central Europe (i.e. Czechoslovakia) never stopped making uranium glass and it's pretty common over there. (Check for "uranium glass" or "Vaseline glass" on EBay). I got the marbles from EBay, a very good deal. I am pretty sure it's not from US origin. But I also have a working "neon" tube that a very old (Chicago) sign company made for me where the central part is made out of uranium glass. Nice effect. I think that the uranium content isn't that high though. I also have a much longer tube from the twenties presumably, where the uranium content is much higher – my Geiger counter will attest of that. Those tubes are most likely from US origin.
If you ever go to Glendale, CA. maybe you should visit the Museum Of Neon Art (MONA) where they have examples of uranium glass on display among other very cool things...
That MONA is a good tip – I will certainly try to make it out there sometime. Nick also mentioned that he did "test" the marbled before he mailed them to me, both with his Geiger counter and by putting them under a UV light – as he says: “The bright yellowish-green fluorescence under UV light doesn't lie.”
Of course this means that as soon as I post this blog I’m going to take a wander around the building to see if I can find a UV light source (I think I recall one of the engineers downstairs has a UV tube hanging over some plants in his windowless office).
It’s only early morning and today is already off to an interesting start… I wonder what the afternoon will bring…