Glass Message Board
Glass Identification - Post here for all ID requests => Glass => Topic started by: rocco on August 30, 2012, 07:20:55 AM
-
I borrowed the UV torch from work the other day, and tested my glass -- which led to some interesting observations...
It was not much of a surprise that almost all my 1950s Skrdlovice pieces containing green colour glowed brightly (pic 1 shows some of them), the same with the green in my Exbor fish (https://picasaweb.google.com/107330317087089352634/Czech?authkey=Gv1sRgCPCtsYSivPC5Dg#5734214732052431698).
But in several pieces even the colourless glass showed distinctive green fluorescence (Skrdlovice Andromeda (https://picasaweb.google.com/107330317087089352634/CzechSkrdlovice?authkey=Gv1sRgCN3F85P1opTf5gE#5677086330712263842) vase, pic 2, and several of my Murano pieces like the Barovier & Toso fish (https://picasaweb.google.com/107330317087089352634/Murano?authkey=Gv1sRgCJ2r4_bjhZ7MXw#5777543559877949138) - pic 3, and the tall smokey grey still unattributed vase (https://picasaweb.google.com/107330317087089352634/OthersUnknown?authkey=Gv1sRgCN-gn4Ga6creDw#5599996929760308018) pic 4).
Even the amethyst-grey casing of this vase (https://picasaweb.google.com/107330317087089352634/Murano?authkey=Gv1sRgCJ2r4_bjhZ7MXw#5599998163243680738) glowed brightly.
My amber Daum etched bowl (https://picasaweb.google.com/107330317087089352634/OthersUnknown?authkey=Gv1sRgCN-gn4Ga6creDw#5666680366420811490) glows green as well, though more obvious in the parts where the glass is thicker...
To my surprise my green A. Seguso bear (https://picasaweb.google.com/107330317087089352634/Murano?authkey=Gv1sRgCJ2r4_bjhZ7MXw#5765031920722801122) didn't really glow brightly -- it looked almost the same under UV than in natural light.
So are there different levels of Uranium content in glass? And why would colourless glass contain Uranium? Does a green glow always indicate Uranium content?
Thanks for any comments,
Michael
-
The pale "glow" is not uranium, but Manganese which was used to reduce the effects of colouring from iron in the metal (I think that's it's use - but it is definitely manganese that gives the green colour with UV light.)
-
I suspect most of them contain manganese not uranium, possibly even your Exbor fish, as it's green doesn't look right for uranium. Did you test them in daylight?
Your green Skrdlovice pieces might contain uranium, but it would be unusual and I would like to judge them without UV.
-
Christine I sometimes find it really difficult to get my camera on the right setting where it will properly replicate the bright green glow on u pieces. Could that be the case here maybe?
m
-
Not with the non-green ones
-
Thanks for sharing your knowledge, very interesting! :)
We had already several pieces in our Skrdlovice thread where the green glass glowed brightly under UV, and the common sense was that these contained Uranium >> Link (http://www.glassmessages.com/index.php/topic,47490.msg271463.html#msg271463)
In my cut pieces from Skrdlovice blanks the green glow is even obvious in daylight >> Link (https://picasaweb.google.com/107330317087089352634/Czech?authkey=Gv1sRgCPCtsYSivPC5Dg#5714979969365520818)
When I tested my glass many of the colourless pieces showed some vague glow in a greenish-yellow colour; but in the ones I showed the glow was much stronger (especially the tall vase in my last pic glows obviously green, and a slight greenish hue is visible in daylight as well).
So do the colour plus the amount of glow indicate if the glass contains Uranium?
Michael
-
Yes! Lots of glow from even the tiniest bit of Uranium.
It can be very hard to capture on camera because the glow itself emanates.... makes all your edges funny and fuzzy.
-
It's not the amount of glow; it's more the colour of the glow. Uranium gives a very bright green glow under UV in daylight no matter how little or how much uranium. It's the same brightness just sometimes more dilute (it's very difficult to explain).
Manganese gives a dull glow and the more manganese the greener it is. I have been trying to persuade myself for a long time that this piece contains uranium (in the base and handle) because you can see green in the base in daylight without a UV light, but I'm sure I'm just fooling myself
http://lustrousstone.co.uk/cpg/displayimage.php?pid=491
What I'm trying to say is that I wouldn't like to say yes to uranium from your pictures
-
Thanks again!
More difficult to jugde than I had thought then...
So maybe none of them Uranium glass, even the (daylight) green coloured pieces?
I have one Murano piece (>> this corroso ashtray (https://picasaweb.google.com/107330317087089352634/Murano?authkey=Gv1sRgCJ2r4_bjhZ7MXw#5660451783140046626)) which glows like mad even with the UV torch 2 metres away, so this should be my reference then I guess...
Michael
-
Quite a few of my Skrdlovice pieces give off a dull greenish glow when I shine a UV light on them in the dark, but only 2 shine brightly, even when I stand a couple of meters away, even in daylight. Those two undeniably contain uranium.
I think the 'stand further away and shine' technique is a good one for distinguishing a manganese glow from a uranium flare. :)
-
I´ve made a similar observation. The Skrdlovice clear glass does indeed have a strong
manganese glow, but also I´m sure they did use uranium. Here´s my example:
https://picasaweb.google.com/108140812446658939096/Skrdlovice#5589252175805496130
BTW are there any other decolorants being used in glass-making? My Gralglas pieces
e.g. glow quite orange-ish under UV. ???
-
If it's orangish green, than that's probably still manganese. I suspect it depends what else is in the glass.
The stand back and shine is probably a good pointer, though it doesn't always work quite so well with irridised pieces or with some of the non-transparent uranium colours
-
I have the same vase as Dirk in the same colourway, and the green layer glows strong like the ones in my other Skrdlovice pieces, so I would think they contain Uranium...
And funnily I observed the strong orange glow in my >> Gral glas bubbly vase (https://picasaweb.google.com/107330317087089352634/German?authkey=Gv1sRgCN_GjOefn6jA7gE#5747242082628486738) as well.
And a totally spooky greenish/turquoise glow came from some of my blue and teal coloured Czech glass pieces.
All very interesting 8)
Michael
-
Re your sommerso jug Christine, I have two, one has a G Hardy label and is red and uranium sommerso, no doubt it is uranium as it glows brightly in daylight with a little UV key ring light. The clear outer layer on both reacts as for manganese, one might make a good comparison photo...
Meanwhile, both these bits of Skrdlovice glow merrily in daylight with a bit of UV. The knobbly bowl has a thin layer of uranium glass 'sandwiched' in the middle.
John
-
I´ve made a similar observation. The Skrdlovice clear glass does indeed have a strong
manganese glow, but also I´m sure they did use uranium. Here´s my example:
https://picasaweb.google.com/108140812446658939096/Skrdlovice#5589252175805496130
BTW are there any other decolorants being used in glass-making? My Gralglas pieces
e.g. glow quite orange-ish under UV. ???
Manganese Dioxide wil produce the orange glow. I've found this particular URL to be helpful. Ken
http://1st-glass.1st-things.com/articles/glasscolouring.html
-
Thanks all! (And Ohio for the link, interesting reading)
So Managanese does produce a green to orange glow ::) doesn't make things easier...
I would now think that the green glass in my Skrdlovice pieces in my first pic does contain Uranium.
The clear glass in the vase in my second pic and the fish could have Manganese glow.
With the tall vase in my 4th pic I am quite sure it is Uranium, too -- not the slightes yellowish hue, and the green glow under UV was obvious in daylight as well...
(My pics are not really convincing I know -- I photographed with the camera in one hand and the UV torch in the other ;D)
Michael
-
Thank you, Ken! That makes sense - I used to have a trinket set, which had both colours under
UV at the same time - greenish orange or orange-ish green... :D