A safe source for tests - vaseline glass

[Richard Hull]

I went with the old gal on Sunday to a couple of large antique malls. I took my small pocket GM counter with me.

I found a really nice, diminuative "depression glass", AKA vaseline glass, cut glass, tooth pick holder, circa 1930. I paid about $12.00 after taxes for the piece. I also picked up a very hot yellow, yellow green trivet as well as a vaseline glass coffee cup and saucer.

Back at the lab, my 2" pancake system and digital scaler showed the toothpick holder ran at about 2800cpm, while the trivet boiled away at about 6,000 cpm and the cup and saucer idled at about 1500 cpm. I supply, below a white light and UV image of the toothpick holder.

These are the ultimate sealed sources for testing any rather sensitive GM counter and even low reading ion chambers.

Unlike the classic Westclox Big Ben or the hamfest, warbird instrument, these puppies are safe for living space storage and use as there is zero radon emission and no transfer of dust or other material common to U rock.

So, for the "Nervous Nelly" looking for a cal source or just something to make the GM counter go over background, antique vaseline glass will do the trick very well and safely. Plus, it is pleasing to the eye.

Note* there were a lot of imitators of the uranium glass, especially post WWII. You need to haul a counter with you as not all yellow green glass is hot. At the prices of today's antiques, you don't want to buy a "cold" pig in a poke. There were U marbles for sale on e-bay at one time, but the ones I got were very unimpressive and only marginally RA compared to true, antique, depression glass.

Another good choice and a lot hotter, but more gaudy and bulky would be the brilliant orange-red Fiestaware ceramic glazed plates and saucers that were all the rage from the late thirties until the late fifites. A large 12" plate of this stuff will top out around 32,000 cpm! Again, no radon and no transfer of material to hands or environment.

Richard Hull

[001userid]

Great information. Several similar items are on e-bay.

I like the aspect of "hiding in plain site" feature this has.

My wife will still be a bit suspicious about why I purchased a fancy piece of glassware.

Joe Sal

[Richard Hull]

I have printed out a large chunk of NUREG 1717. This is a government document that looks at NRC exmepted source and byproduct materials to determine probable levels of public exposure over a range of probable conditions which might be encountered in the public domain.

In some experiments actually conducted on vaseline glass, they noted that using water and acidic juices, some leaching of Uranic materials occurred but that following only 3 such 24 hour leaches, the liquids no longer carried off measurable amounts of uranics. It seems that once leached, the surface uraninics were depleted and all other contained material was locked in the vitrified glass. Remember, they used acids such as 1 molar nitric and let them stand for 24 hours and even then only obtained an average of 14ug/liter of leach on the first pass and far less on subsequent passes!

You are going to fill the glass with some sort of swill and drink it in minutes, thus, no effective leach. For the paranoid who want to use the stuff at the dinner table, a nice 2 day leach each with muriatic, sulfuric and nitric concentrates will leave the glass free of any surface uranics so that even baby Jane could swill her juice in safety.

It was noted that even the first leach maximums were all within human consumption ranges and that a lot of public water supplies gave more radiation that the first vaseline glass leach contained.

This stuff is very safe.

Richard Hull

[Christopher]

Vaseline glass toy marbles are currently being offered on ebay for £3.50 (US $7) for ten by a number of vendors. I understand these are not antique, but are contemporary items manufactured using depleted uranium.

[Richard Hull]

I mentioned those marbles in my first posting above. I have piles of them here and am not terribly impressed. I just guess it depends on how hot you want your source to be.

Richard Hull

[Wilfried Heil]

This is another nice example which has survived the time from the uranium glass era. Such glass was made for about 100 years, from its invention by J. Riedel in 1826 to ~1940, when uranium became a strategic resource.

Works well as a check source but has found other uses since.

Uranium Glass and its Scientific Uses: >http://www.sis.org.uk/bulletin/92/Brenni.pdf