OT: Radioactive clock

[Paul Andrews]

I thought you all might find this amusing. I while back there was a thread about tubes with radon in them. That set me off on a little side-quest where I ended building a Geiger counter using an old Russian Geiger-mueller tube. It has never detected anything but background levels.

I also buy other vintage stuff, and my wife just asked me to check one of them for radioactivity, because she said “it looks like it glows”. It had never occurred to me. Anyhow, here is the result:

https://youtu.be/PMrHIyntT4s

[gregebert]

And just because it no longer glows, does NOT mean it's no longer radioactive. Radium half-lifes in 1600 years; the 'glow agents' deplete after a few years.

I dont know how dangerous these items are, though. Radium undergoes alpha particle decay, and those particles are easily stopped. Even a paper bag will block alpha particles. But if you were to ingest an alpha-particle emitter, that will be bad.

[SWISSNIXIE - Jonathan F.]

Nice to see other people with interest in radiation :)

The clocks are probably radioactive because of their paint on the watch hands. In the 1930's they used radium paint to make night glowing watch hands. Radium contains radioactive isotopes (Ra-226)

Before people got silly about radiation, radioactive material was used for quite a few consumer products like watch hands, vacuum tubes, uranium glass pottery, lantern mantles.  Running around with a scintillation counter (more sensible geiger counter) on a vintage flew marked will usually bring up some items :)

[Paul Andrews]

At 1 foot from the dial, the count drops to 500CPM - a 10-fold decrease but that still seems quite large to me. BTW, it looks like this was painted all over the dial on this clock. I have another variation of this clock that only has it on the hands. CPM is the same though. I also checked a radio/alarm clock from about 1960. It too is radioactive, but an order of magnitude less - or maybe the plastic covering that clock is stopping more of the particle.

Yes, none of them glow in the dark any more. Is there something I could get that would light up under the bombardment? Like some glow-in-the-dark paint? It would be fun to mess with this a little.

[Paolo Cravero]

 

Yes, none of them glow in the dark any more. Is there something I could get that would light up under the bombardment? Like some glow-in-the-dark paint? It would be fun to mess with this a little.

You could try with UV light, even the UV LED from a cheap "magic ink" toy pen could do. I've tried on a "self-luminous via" and the green element glows more, then there is a slow decay effect when the exciter light is removed (but that could be persistence of vision in the eye).

Not everything that glows green under UV-light is radioactive, but I think the other way around holds true.

Paolo

[Terry Kennedy]

For a while I was buying up Elektronika clocks from the ex-Soviet Union. When I received them, I'd replace the VFD tubes and otherwise freshen them up. One of them was full of the nastiest, grittiest dust imaginable. When I asked the seller what was up, and where it came from, they replied "a disused industrial premises approx. 100km NNW of Kiev". AKA Chernobyl. 

[HuggerMugger]

I saw what the radium did to people in a documentary about the period of elements:

https://en.wikipedia.org/wiki/Radium_jaw

Radium is closely related to Calcium and hence the body absorbs radium and stores it where radium use to be stored – in the skeleton. and most often in the jaw bones.

 

/Magnus

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[alb.001 alb.001]

Many of the workers who painted the watch hands etc died of radiation poisoning in the early 20th century.  Marie Curie who discovered radium also died of radiation poisoning.

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[alb.001 alb.001]

When I was a teen-ager in the 1960's I bought a radiation experimenters kit which had a small device which looked like a watch-makers eyepiece except it had a screen in the front which fluoresced under radiation. It was called a spinarthroscope.  The kit included a small piece of uranium ore.  In a dark room, you put the device on your eye and held the uranium up to the screen and could see green flashes caused by the radiation interacting with the screen at the front.  

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[Terry S]

Guessing you might not get that thru airport security now days.

[Paul Andrews]

How's the eye?

[alb.001 alb.001]

I have bad floaters in my right eye   related ??

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[SWISSNIXIE - Jonathan F.]

Spinthariscopes are very nice!
You can still buy them! http://unitednuclear.com/index.php?main_page=index&cPath=2_12

About the danger:

There is literally no danger about the scope, because the particles you see are mostly  alpha-radiation that do not pass through the looking glass. Alphas rarely can pass paper...
Also Radium in clocks would only cause potential danger if you would keep your clock all the time in your pocket - or whats way worse - the radium would get out of the clock and into your body.

[marta_kson]

philthepill wrote:

Many of the workers who painted the watch hands etc died of radiation poisoning in the early 20th century.  Marie Curie who discovered radium also died of radiation poisoning.

Don't scarry up people too much...
Those poor workers was not informed that ingesting the paint meant goodbye, so they wetted the fine brush in thier mouths to have a nice fine point to paint with...
Marie Curie did _not_ die from radium, that is a common misconception. She volunteered as a nurse during the great war and died from X-ray exposure.
Good luck with the clocks. Maybe there will be some modern age tritium paint available somewhere to touch them up.