type of lume on e.g. Westclox Big Ben clocks?

[Harold Davis]

Does anyone know what kind of lume Westclox used on their alarm clocks, e.g. the Big Ben and Baby Ben? Radium?

Harry

[Harold Davis]

Harold Davis wrote in news:XnsA3DA8C079F40Fharolddavis@213.239.209.88:

Answering my own question here: yes, they did use radium.

Just found this, showing someone using a Geiger counter:

Yikes! I wonder whether they stopped before the last few years of production, when even they were making crap.

Harry

[GB]

Oh dear! I had one of those fifty+ years ago, so it must have been radioactive.

[Chris Hogg]

Some info here

but as long as you don't open the clock up and start scraping off the luminous paint, thereby risking ingesting the dust in some way, there's absolutely no cause for alarm. Radium emits beta and gamma rays. The beta's won't get past the clock glass, and the level of intensity of the gammas won't do you any harm. Just remember that lots of things are naturally radioactive; bananas are the usual example people quote: It is even suggested these days that low doses of radiation are actually beneficial, and there is some evidence in support of that.

[Martin Brown]

You have it wrong. Radium primarily decays by alpha emission as does the next in line Radon - these short range energetic particles make th ephosphor glow. After that there are beta decays in the daughter decay chain and various impure reactions with betas and gammas which will penetrate the glass easily but at a much lower intensity.

So long as you don't eat the thing you should be OK. The girls who licked their brushes to get a fine line were not so lucky nor was Eben Byers the man who had to be buried in a lead casket for Radithor tonic.

[Robin]

Yerrbut they didn't tell little boys that in the 1950s. (It was a broken clock m'Lud!) And when I mixed it with glue it didn't stay stuck to my torch for more than a week or two. So all in all probably on a par with so many of my DIY efforts subsquently.

[Richard Tobin]

When I was at school, we had a physics teacher who would always go out for a smoke in the middle of the lesson. He did this during an experiment to measure the half-life of protactinium, so I went up to the bench and put my watch next to the GM tube, which increased the measured rate by a factor of ten or so.

-- Richard

[F Murtz]

I have a little bottle of the stuff somewhere, glows green, moreso if you put it near light first.

[Chris Hogg]

I have a small collection of uranium glassware. It was popular in late Victorian and early Edwardian times, contains about 2% uranium oxide and is radioactive. It glows nicely in UV light (so called black light, popular for disco lighting). Plenty of uranium glass on Ebay, e.g.

[Andy Burns]

Shame it all looks like the stuff nobody wants when granny pops her clogs :-)

Maybe I'd give one or two of the Murano sommerso pieces a home ... maybe.

[Martin Brown]

Uranium is a lot more common than most people think.

There is on average about 2ppm in most things and even more in granite. Marie Curie got her radium from the tailings of pitchblende used by the glass industry for its uranium content. She spotted that it was more radioactive than pure refined uranium and set about finding why.

What is very rare is mineable quality uranium ore bodies.

[Chris Hogg]

Well, yes, although some of it isn't too bad. I have it just out of technical curiosity, and the possibility that the uranium might have been mined locally to me in Cornwall, as much of it was. See

(The reply, to the original New Scientist question, was from me).

I imagine that modern uranium glass is made with depleted uranium.

[F Murtz]

Not that it is the same thing,but I watched them put a container of glassware down in the heavy water tank with the fuel rods at Australia's reactor, and when they removed them they all had variegated colours through them.

[Chris Hogg]

I have a similar experience. Many years ago (~1970) I was involved in an experiment to study the effects of gamma radiation on the colour of china clay. A small glass sample bottle containing china clay was exposed to a powerful Co60 source for 24 hours. The bottle went black, but the clay colour was unchanged. Something to do with electrons displaced in the glass structure having optical absorption in the visible region. Amethyst is similar. See

and scroll down to Synthetic Amethyst. Heating allows the electrons to return to their proper positions, and the colour fades, although I don't recall we tried it with the glass sample bottle.