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Author Topic: weird UV glow color and pattern on cased Harrach pitcher = Cadmium sulphide  (Read 1692 times)

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Offline krsilber

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I got a matching pair of Harrach 10 1/5" pitchers yesterday.  The inside is pink.  Over that is a layer of opaque white.  Then I believe there's a thin layer of dense, fairly translucent yellow, and on top of that, colorless.  Either that or the top layer is actually yellow, but I don't think so.

Last night I turned the UV light on it, not expecting much - the yellow doesn't really have the tone of uranium.  But wow, did it glow!  Not green - ORANGE!  Bright orange.  I'd noticed in the past a tendency for colorless Bohemian glass to glow a dull, dirty orange, but nothing like this.  And the pattern of the the glow was also interesting:  part of the neck up to the rim glows brightly, and about the bottom 1/3 of the body is also bright, but not quite as strong.  The rest seems to have a faint greenish color.  And there's one spot on the bottom where the pontil has been ground to the white that glows purple (and it's not just a reflection of the UV bulb), so it's got to be one of the upper layers that's glowing orange.  There's no obvious difference in the glass between what's orange and what's not.

Has anyone else seen a bright orange glow like this, and on what?

Photos:  Some are in my gallery, some not.  Here's the whole pitcher in normal light:
http://glassgallery.yobunny.org.uk/displayimage.php?pos=-9961
Here's the bottom of it:
http://glassgallery.yobunny.org.uk/displayimage.php?pos=-9960
And one of the inside.  The pink appears to be throughout the interior, though it's a bit hard to tell.
http://glassgallery.yobunny.org.uk/displayimage.php?pos=-9962

Below is a photo of the pitcher in UV, then a couple with a uranium custard glass cased basket for comparison, one in UV and one in normal light, just so you know my bulb isn't funky! (I would like info about the basket, if anyone knows anything about it.)  In the UV photo there's also a Heisey jar that's got a nice manganese glow to it, but it's overwhelmed by the glow of the other pieces.  You can sort of see the spot in the middle of the bottom of the pitcher that is purple, though you can't really tell how purple it is.

The other matching pitcher has pretty much the same pattern, though the glow on the neck extends further down.
Kristi


"The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science."

- Albert Einstein


Offline Anne

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Re: weird UV glow color and pattern on cased Harrach pitcher
« Reply #1 on: May 08, 2008, 08:55:38 PM »
Cadmium sulphide http://www.glassmessages.com/index.php/topic,95.0.html :) (Thanks to Glen for the earlier info. )  My amberina goblet glows orange at the base (the yellow part) too.


Offline krsilber

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Re: weird UV glow color and pattern on cased Harrach pitcher
« Reply #2 on: May 08, 2008, 09:07:58 PM »
Thanks, Anne!  It had actually crossed my mind that it might be cadmium.  It must glow only with specific valences, as Tom said (I know that Tom!), otherwise there's be a lot more glowing orange stuff out there.  Unfortunately, Glen's article link doesn't work anymore, and your photos are all gone.  Maybe Glen will see this and provide another link to her article...and I'd love to see your amberina goblet!
Kristi


"The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science."

- Albert Einstein


Offline Anne

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Re: weird UV glow color and pattern on cased Harrach pitcher
« Reply #3 on: May 08, 2008, 09:25:04 PM »
Psst Kristi, Glen's a gal! ;)  Goblet pic to follow. :)


Offline krsilber

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Re: weird UV glow color and pattern on cased Harrach pitcher
« Reply #4 on: May 08, 2008, 09:46:29 PM »
Oops, thanks for the correction!  I edited my post to reflect that.
Kristi


"The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science."

- Albert Einstein

Offline Frank

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Re: weird UV glow color and pattern on cased Harrach pitcher
« Reply #5 on: May 08, 2008, 11:39:14 PM »
In the 19th century the structure of the Bohemian glass industry, separation of blowing and decorating led to a distinct difference in the glass composition, Commissioner Blake reported in 1878 that the typical composition of Bohemian White glass was:
Pulverised quartz (Plentiful compared to sand) 100 parts
Carbonate of Potash 28-32 parts
Slacked lime 13-15 parts
Oxide of Manganese 1 part
Arsenic 3 parts.

This white glass was harder then American flint glass. Such variations are likely to result in different fluorescence then found elsewhere. Carbonates tend to fluoresce in the yellow region, Quartz is variable depending on source, Lime is again a yellow fluorescent, while Manganese gives pink which combined presumably (speculation) looks pinkish orange.
Frank A.
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Offline Galle

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Re: weird UV glow color and pattern on cased Harrach pitcher
« Reply #6 on: May 09, 2008, 12:28:32 AM »
I just sold this Franz Welz piece on eBay - very similar glow:  :chky:

Congrats on the Harrach pair, Kristi - I was asleep on that one.  :hiclp: :mrgreen: :hiclp:

Offline krsilber

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Re: weird UV glow color and pattern on cased Harrach pitcher
« Reply #7 on: May 09, 2008, 02:21:48 AM »
That's a mighty pretty piece, Warren!  Nice glow, too!

In the 19th century the structure of the Bohemian glass industry, separation of blowing and decorating led to a distinct difference in the glass composition, Commissioner Blake reported in 1878 that the typical composition of Bohemian White glass was:
Pulverised quartz (Plentiful compared to sand) 100 parts
Carbonate of Potash 28-32 parts
Slacked lime 13-15 parts
Oxide of Manganese 1 part
Arsenic 3 parts.

This white glass was harder then American flint glass. Such variations are likely to result in different fluorescence then found elsewhere. Carbonates tend to fluoresce in the yellow region, Quartz is variable depending on source, Lime is again a yellow fluorescent, while Manganese gives pink which combined presumably (speculation) looks pinkish orange.

There's that ambiguous "flint" word!  I was just reading a flint thread from the archives.  Do you mean American lead glass?

Are you basing these glow colors on how they appear in glass, or on raw minerals?

Manganese in American glass fluoresces greenish.  It's actually an activator in its mineral state and fluoresces differently depending on what it's found with.

While some lime fluoresces yellow in its natural state, it can also fluoresce other colors depending on "contaminants."  Lime glass doesn't necessarily fluoresce at all.

I didn't know that about the quartz.  That's interesting.  I imagine minerals found in the quartz could affect its glow color.  That would explain the relatively wide variation in colors I've seen my colorless Bohemian glass fluoresce.

Baldwin in Moser Artistry in Glass compares the way Bohemian "crystal" (leadless), Venetian crystal (ditto) and European lead crystal glow in shortwave and longwave UV light.  Apparently using the combination he's able to differentiate among the three.  He also gives a formula for Bohemian crystal similar to the one you posted but with soda (NaCO3) as well. 

I'm fascinated by the variation in the way glass glows in UV.  It's something of a controversy in the US whether it actually means anything, or whether it's useful in attribution.  I think it can be useful as a tool as long as one is careful about the conclusions one draws from it, and is knowledgeable about it.  Glass chemistry is so complex that making inferences about what it contains based on glow color under longwave UV alone is really hard.  Manganese, for instance, will only glow in a certain valency state, which is why amethyst glass doesn't glow.  In colorless glass it oxidizes (or reduces, I always forget) iron, and in doing so becomes UV reactive.

I suspect the valency state of cadmium is heat-dependent, and that is why only parts of my pitchers glow bright orange (and only the amber part of Anne's goblet).
Kristi


"The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science."

- Albert Einstein

Offline KevinH

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Re: weird UV glow color and pattern on cased Harrach pitcher
« Reply #8 on: May 09, 2008, 03:00:24 AM »
Quote
... It's something of a controversy in the US whether it actually means anything, or whether it's useful in attribution.  I think it can be useful as a tool as long as one is careful about the conclusions one draws from it ...

I agree that UV analysis is a good tool when used with care and understanding. And I believe that UV results cannot be used for basic attributrions - unless, of course, we know the UV reactions for every piece glass made by every maker over all time since glass was first utilised. If we had all that data, we may then find that a particular maker's items do show a truly unique UV reaction and therefore that result could be used in an attribution.

But on the basis of use as a tool to assist in other observations, UV can show definitive results. For instance, by using both longwave and shortwave I was able to show that Ysart paperweights could be sorted into distinct periods. By that means, the three main periods of Paul Ysart's output can be identified, as can the two periods of "Early Vasart" and "Later Vasart". That seems to be pretty much the same sort of 'dual UV analysis result' as Kristi has mentioned for "Baldwin in Moser Artistry in Glass". However, for the Ysart weights, it is still not possible to use those UV results to separate Paul Ysart items of the 1930s-1950s from "Early Vasart" work - as they fluoresce in the same basic colours under the respetive wavelenghts.

On the general subject of orange fluorescence, I am fairly sure that there is an interesting orange glow at the edges of the cut areas (!) in my couple of "Egermann style" ruby-flashed items. I must check that out some time.

Edited to add:
Sorry - I was wrong - it's not an orange glow on the cut pieces. It's actually a bright, pale yellow! And that's under shorwtave UV. For longwave, much of the cut parts, not just the edges, shows as a weak orangy-yellowy-greeny colour (depending on how long I stare at it).
KevinH

Offline krsilber

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Re: weird UV glow color and pattern on cased Harrach pitcher
« Reply #9 on: May 09, 2008, 05:28:17 AM »
I was just reading an old thread on UV here http://www.glassmessages.com/index.php/topic,1263.0.html and noticed you were interested in it, Kevin.  I've been thinking about starting a thread on it myself, but don't know if it's already been talked to death around here.  I was interested in whether rich cut glass made over there glows, and what color.

I have a theory about your cut areas glowing.  Hmm, no two alternate theories.  One is that the outside of the stain got hotter than the inside, resulting in different valences of selenium.  But that seems unlikely.  How about the stain nearest the glass fused with it, resulting in a chemical change that causes glowing.

This is stained, right? Wait, you said flashed.  Can you post a photo?

I have a Bohemian cut and engraved piece with an amber stain that glows bright orange in LWUV.

I'm so glad to hear you say "Egermann-style"!  Americans don't seem to understand that others besides Egermann made/make the stuff.
Kristi


"The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science."

- Albert Einstein

 

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