Topic: Do you have UK cut glass and a UV light? A favour, please...

[krsilber]

I wonder why they would have used manganese in those cases.  Will wonders never cease?  (Hope not!)

[crystalclear]

Yes krsilber that would be T.B. Clark, it has glowed (if you can use that word) the brightest of any piece I have ever had.

Some interesting notes I just viewed my Libbey bowl under black light, no glow which is no surprise it is from the later period of the flowers.

But where 2 stems meet on the bowl, they glow orange.  Its not dirty so can't be that.

Another celery from the flower period is a pale yellow.  The Clark I was talking about was a dirty lemon color, bright for ABP.

Take back what I said before, there is a piece I do not know the maker, it is a perfume and the sterling silver marks are Birmingham, this glows a pale green glow.  Mark on the silver is around 1911.

[krsilber]

Yes krsilber that would be T.B. Clark, it has glowed (if you can use that word) the brightest of any piece I have ever had.

Some interesting notes I just viewed my Libbey bowl under black light, no glow which is no surprise it is from the later period of the flowers.

But where 2 stems meet on the bowl, they glow orange.  Its not dirty so can't be that.  Could it be that you are seeing the effects of a very faint overall glow better in that spot?  Often it's brighter in cut areas.

Another celery from the flower period is a pale yellow.  The Clark I was talking about was a dirty lemon color, bright for ABP.  I don't know off hand and don't have time to try to find out, but it's possible Clark imported some of their blanks.  That might account for the different color.  I'll look into it but it might be a few days before I can get back here.

Take back what I said before, there is a piece I do not know the maker, it is a perfume and the sterling silver marks are Birmingham, this glows a pale green glow.  Mark on the silver is around 1911.
 
Sounds interesting!  Do you have any photos of it?  Even one with normal light would be nice to see.

The trouble with photos of glass under UV light is that you really can't compare colors accurately, except perhaps among a group of glass in the same photo or at least taken by same the camera.  They're too dependent on camera settings and other factors.

[crystalclear]

No Kristi

The libbey bowl does not glow anywhere else, just where the 2 stems meet and I mean a bright orange like the fruit.  Never noticed that before.

The perfume is running in an auction and I will post the piece as soon as it is finished.

I think I need to learn how to keep my shutter open longer on my camera when I take a picture so that I can capture the colors of the glass under UV light.  Have to do some research on that one, because you have to see this orange.

As far a Clark, yes you are right they did import some of their glass.

Now I had a Neola bowl from libbey that was cut and it was pale yellow under black light.

[krsilber]

I have a Boston and Sandwich engraved bowl that glows pale yellow, too.

The Libbey is a curious one.  Can you post a picture in normal light?  I'd like to see where on the bowl they come together.

I have had pieces of green and blue non-uranium pressed glass with the manganese glow

This is bugging me.  Were the colors particularly pure?  I can't see why you'd use enough manganese that you'd see a blue item glow green.  Is it used for something besides coloring and decoloring?

What kind of pieces were they?

That blue uranium Fenton piece of Mark's is pretty cool.

[Lustrousstone]

The were just relatively low quality bits of pressed glass, probably from pre 1950. I don't have them to hand, I may not even have them any more. I am pretty certain that this is an example (BTW it's not Bagley, it's either Czech or Walther, don't have time to look now) hereThe glows in the dark is a clue, if you have to be in the dark to see the glow it's manganese

[Frank]

Is it used for something besides coloring and decoloring?

Yes, it was also used as an oxidising agent to help decompose any organic elements, but not an important one.

As to colour its effects vary with the level of oxidisation and can be used, with other materials, to give Reddish Violet, Bluish Violet, Brownish Violet, Indigo Blue, Reddish Brown, Grey and Black in Soda Glass. For lead glass - Red Violet, Blue Violet and Grey.

Arsenious Oxide was used to reduce the colouring effect of Managanese Dioxide used for decolorising. Black glass is a combination of high levels of Manganese Dioxide and cobalt iron or copper oxide.

As a decloriser it was more effective in Potash Glass than Soda glass, effective with lead glass melted in a pot but not in a tank. The effect of reheating tends to reduce the colour so this reduction had to be taken into effect when preparing the batch.

All of the above are gross simplifications of information in Cousen and Hodken. The reality is that its effects are subject to a huge range of parameters and in 1925 the knowledge was largely sketchy based on observation and experience rather than research.

Nickel Oxide was used for decolourising instead in Germany.

A remarkable material.

[krsilber]

Yes, it was also used as an oxidising agent to help decompose any organic elements, but not an important one.

Could this me simply an extension of its action as a decolorant?  Oxidation is the way it neutralizes the coloring effects of iron.

effective with lead glass melted in a pot but not in a tank.

  I believe lead glass was usually melted in covered pots.  Otherwise reaction with the atmosphere cause the lead to come out of solution and precipitate.

The reality is that its effects are subject to a huge range of parameters

  ...like so many of the constituents of glass!