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Glass Identification - Post here for all ID requests => Glass => Unresolved Glass Queries => Topic started by: Galle on November 11, 2008, 07:41:13 PM
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Has anyone seen anything like this? The applied feet wrap up around the piece and merge into the rim and are amber, blue, and green. There is some uranium in the green and blue, and some amount of (manganese?) in the amber, because under strong black light, the blue and green glass glows green (slightly) and the amber glows orange (slightly).
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I doubt there is any uranium in your pretty little vase, uranium never glows faintly. Faint green may be manganese and I think orange is cadmium. That blue and amber combinations seems common on Harrach items
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Hmmm I never thought about that (the uranium issue)... I just never realized that any other thing caused a greenish glow.
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I often see these types of pieces called Moser Harrach. Personally I believe yours is Harrach. The amber is paler than many of the vases, but the stems and flowers look Harrach to me.
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Thanks, Anita - I've been leaning towards Harrach myself. I didn't know if S&W ever did anything similar. :)
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If it were just a little uranium, might it not glow faintly? Although I've seen green glass formulas with manganese, it doesn't seem common, and the colorless Bohemian glass I have doesn't glow green. I don't know if that's because they used different decolorants or what. The colorless glass I have that glows green rather than a yellowish green glows really quite faintly; I'm not sure you'd be able to even see it in green glass. You can only add so much manganese before you start getting purple.
The glow color of glass is probably more complex than many glass enthusiasts (myself included!) have made it out to be. There are so many confusing factors, such as multiple fluorescent substances and the role of absorption of light by some materials. You could have one substance emitting light and another absorbing it. Or contamination could influence things, as in this little snippet from this article (http://www.cstl.nist.gov/projects/fy06/indst0683101.pdf):
"However, there was a problem, most known fluorescing metal oxide dopants [I wish they said what they were!] failed to produce fluorescence in our glass. This turned out to be caused by impurities from the ingredients used to make the glass and from the inexpensive silica/alumina crucibles we were then using."
Geez, I see a quick mention of fluorescent glass, and can't stop myself - blab, blab, blab!
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No Kristi, the uranium glow is quite distinctive but quite difficult to describe. It's almost like the difference between an LED fairy light bulb and an old fashioned tungsten one. The two greens are quite different shades, so even if the the level of uranium is low you can tell the difference (what you see with lower levels of uranium is perhaps best described as a colour wash rather than thick blob; you know it's the same bright green colour). Even with an LED light you get a reaction 2ft away. For the faint green glows you have to get up close and personal and possibly in the dark. Green and flint (clear) glass that has the faint glow is not uncommon here in the UK but it is often early/mid 20th century stuff. I spend many happy hours checking stuff out in my searching.
If Galle's green contained uranium, I would expect a bright glow for that shade; if the blue contained uranium you would be able to see a hint of green in the photo. It is just too blue.
Hope this makes sense :spls:
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I have uranium glass and know what the glow looks like. Pieces from Dave Peterson's collection vary in intensity.
Green and flint (clear) glass that has the faint glow is not uncommon here in the UK but it is often early/mid 20th century stuff. I spend many happy hours checking stuff out in my searching.
That's interesting, I've often wondered about that. Is it a green glow or a greenish yellow? What about older English pieces?
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I'll see if I can capture the effect with my camera - it's a little tricky. :)
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I also wanted to say regarding the glow that I have noticed that Loetz Creta glass (Creta Rusticana, for example) has the same type of "slight" glow - if the black light is held right up to the piece, you can see a distinctive glow, but it is nowhere near the brightness of, say, Oceanik.
I also have some examples of clear or slightly purple glass that produce the same effect - nothing from a distance, but up close, the green starts to show.
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If it's the same kind of glow you find in colorless glass, then Christine's right, it probably isn't uranium. If you can see that in blue or green glass, it makes me wonder how many people out there think their green glass contains uranium when really it's something else glowing.
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Here we go... best I could do... First pic is the green leg, second pic is the blue one, third pic kind of shows both green and blue legs and the amber glass in between.
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That's the manganese glow.
Kristi, lots of them. I see it on ebay and online shops all the time and nearly as many of them know it's got uranium in when they admit they haven't got a black light! When you collect uranium glass you get an eye for it in photos, not an infallible one I admit but...
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Good discussion - one more question and I'm done... does the use of manganese in a piece like this one give any additional clues to its origin? I still think Harrach is the more likely player, but I'm now wondering if it there is a chance this could be a French piece.
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The answer is no, glass composition in itself does not point at a region or country of origin. Only if you have two glasses, one of known and one of unknown origin with the same characteristics can you draw the careful conclusion that these might be related. Possible makers for this piece will include Sevres, Meisenthal, Valerysthal, Pantin, Clichy, Legras and Auguste Jean - apart from the usual Bohemian suspects.
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Thanks, everyone. :thup:
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As some of you know, glass composition and glass fluorescence are particular interests of mine. So if I tend to ramble on about them and ask lot of questions, that's why. ::)
I'm sure there's a lot of green glass on ebay that is said to be uranium glass but isn't. Still, I think a lot of it one wouldn't expect to contain U based on the photos (I wouldn't, anyway). I was just reading some old threads in another forum, chataboutdg.com, about green fluorescent Depression glass. Unfortunately, you have to be registered to see them, but here are the threads for those who are registered or would like to. It's an excellent board if you have anything you suspect is American Elegant or Depression.
http://chataboutdg.com/invision/index.php?showtopic=8290
http://chataboutdg.com/invision/index.php?showtopic=8124
http://chataboutdg.com/invision/index.php?showtopic=8366
Mod: links no longer work after website reorganisation.
There's a married couple there who collect transparent green Depression glass and they're quite interested in the causes of fluorescence. Much of their glass contains uranium. I'm not a collector of uranium glass, and don't have the eye for it that others would, but FWIW some of it I wouldn't have pegged as uranium. A couple pieces I used to own are shown below, a Tiffin center handled server and a Cambridge bowl. Both looked pretty normal (to my eye) under most light, though they'd glow a bit at dusk.
Cambridge's Willow Blue also had uranium in the formula:
The green glass collectors have a shortwave UV light as well as a longwave. They showed a couple photos of a sugar and creamer set that glowed bright green in LW UV, but in shortwave, one glowed green and one glowed bright blue! A good example of glass formulas changing over the years.
This is irrelevant, but neodymium is used as a decolorant sometimes, and is supposed to fluoresce in LWUV. Does anyone know what color?
Concerning different glass compositions in different regions, Gary Baldwin in Moser Artistic Glass reportedly used the combination of shortwave and longwave UV to discern among 3 glass types: Bohemian potash-lime, Venetian soda-lime, and European lead crystal. Apparently most Bohemian non-lead glass formulas from about 1850-1930 were based on one by Meyr's Neffe. Although he seemed to be aware that you have to be careful with your testing, it's hard to know what range of glass he used, and how many replicates. It would be nice to know if his results were reproducible.
Incidentally, he also found a gradual change in the shortwave fluorescence color of Moser through the 20th C...makes one wonder about the use it might have in dating if something like that could be properly documented.
Mod: Links to clicksnipwow removed as site is no longer connected to glass. Please visit http://chataboutdg.com/forums/ and use the search function instead
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The edge shots are generally the giveaway for green uranium glass - can't tell from yours
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I guess that's an indication that it's sometimes hard to tell in things like ebay listings. Here are a couple shots of another Cambridge piece, two different backgrounds. It seems like there's kind of a nondescript glow in the edge of it, and also when you look at the edges of the stack of Willow Blue Cambridge plates in the second photo. But that could just as easily be due to the light and other colorants. Did you see the Willow Blue collection?
(These photos are from my early days of glass photography!)
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Yes that's what I mean, it's a sort of hazy glow rather than a sparkle. Not convinced by the Blue Willow at all, I would expect a tiny hint of a green glow
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I've been trying to find out where I got the idea that Willow Blue contained uranium. I know one of the members in the other forum (I noticed you're registered there, Christine) said that he had a Willow Blue piece that glowed really brightly, but then he showed a photo of one in UV and it didn't seem very bright at all. Maybe it was my imagination that I saw uranium in a Willow Blue formula. Actually, he's a member here; maybe I'll email him and get him to poke his nose in, he knows a lot about Cambridge.
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While looking in the Weitzman book on crackle glass (for something else) I came across a piece with this exact same shaped bowl, and four tadpole feet instead of three - different enameling, but shown as a piece by F.E. Rousseau. As much of Rousseau is unsigned, this seems like a good lead to me... anyone familiar with Rousseau?