Topic: Thomas Webb — heat sensitive? — akin to Alexandrite?

[flying free]

 thanks for the explanation Christine I could not remember how it was done.  I think you have explained this before and that there are a couple of threads on here with some further discussion on that casing method but I couldn't find them.

edited to add: 
With regards the definition of Webb Alexandrite, I understand it that the base glass is uranium and that the rim should show as chocolate at the very edge when angled.

There is a good description here from Kev regarding Stevens and Williams Alexandrite.  I read this as the colour effect not being achieved via a reheating method but by casing of glass in various colours -
http://www.glassmessages.com/index.php/topic,563.msg2430.html#msg2430

'As for "Alexandrite", again Revi describes this well enough - at least for the Thomas Webb version. It was a term used for a tri-coloured shaded glass (amber - rose - violet) formed by two reheatings. Stevens & Williams apparently used the same name but Revi's description, "plated transparent yellow with rose and blue" differs from Manley's, who stated "cased Rockingham [a chocolate colour] over citron over crystal". Hajdamach seems not to cover "Alexandrite" for Stevens & Willams.'



and on the Fairy Lamp site Jim has added a page with all references found at that point, to Alexandrite glass from Thomas Webb and includes descriptions of Stevens and Williams cased Alexandrite glass
http://www.fairy-lamp.com/Fairylamp/Temp/Alexandrite_References.html


Nigel has handled and owned a number of Webb Alexandrite pieces and given a very clear description of Thomas Webb Alexandrite here (btw subsequently in that thread he determined the fairy lamp was indeed Webb Alexandrite)
http://www.glassmessages.com/index.php/topic,9368.msg79563.html#msg79563

m

[Lustrousstone]

I don't think the rims should show chocolate; some items do but glasses generally do not and they needed to match. They were also easy to hold and reheat with their vertical bowls, so I suspect that whatever was achieved with this expensive metal was OK, except for glasses
http://lustrousstone.co.uk/cpg/displayimage.php?pid=1780

[flying free]

I had just been going by what Nigel had said in the post I linked above regarding the chocolate rim.
This one is wine glass shaped 4 1/2 " tall, and has the chocolate rim. 
http://www.shop.glasstiques.com/Alexandrite-Stem-Glass-1794.htm
m

[chopin-liszt]

I was under the impression that if the rim has gone as far as chocolate, the thing has been overcooked during production. They were supposed to stop when it had gone blue.
Obviously, with it all being red-white hot, it was very hard to tell when that point had been reached. 

[Lustrousstone]

That's an optical illusion from looking into the metal itself. I've just checked my glasses and they show it , but not from straight on and held against the light.

[Paul S.]

having looked at Parts 1 and 2 of the Christie's catalogues for the Parkington collection - the items referred to by Nigel in m's link - can say that the images of the pieces in question are too small to reveal any chocolate colouring.            Contrast in the pix is good though, and shows the main deep rose/purple/fuchsia/violet blue signature colours of Alexandrite to good effect, with one piece appearing to show an excess of blue due to over-heating.             
Michael Parkington had some very choice pieces of Alexandrite - one of which was a tall wine which, very unusually for this material, showed the re-struck colours at both the bowl rim and foot rim.

As we know, it's the gold in solution, apparently, that is responsible for the Alexandrite colours when re-heated - I wonder if it was 24 ct. - and of course the same ingredient is responsible for the pinks in Burmese.   
Both contain uranium (will someone please reconfirm that Alexandrite does glow please), although Burmese has other ingredients to give the opacity etc.

Before I was aware of the Truits comments that they believed the manufacture of Alexandrite was confined to the U.K., I looked in Kenneth M. Wilsons volume one of 'Mt. Washington & Pairpoint Glass' expecting to see reams of the stuff, alongside Burmese and Peach Blow etc., but nothing, despite an entire chapter on the history and litigation surrounding Locke's invention of Amberina.
Which I thought was odd, since surely someone in the States, making Amberina, would have heated twice and discovered those colours beyond Amberina which we now call Alexandrite.

It seems that in order to profit from what had become an explosive market for Amberina (the 1880's) and avoid legal issues with New England Glass Works (Joseph Locke), Mt. Washington made their own product called Rose Amber - although the two products appear mostly indistinguishable, with a possibility that some Rose Amber looks decidedly more fuchsia than ordinary Amberina.
I believe that the States Amberina and Rose Amber were both of lead glass manufacture, but I don't know if this was also true of Alexandrite.

The Alexandrite pieces in the Grover's volume are interesting and definitely worth a look, and include plates, one of which exhibits much blue around the rim  -  although in view of the date of the book the picture quality is not too good.      These authors give a brief account of the re-heating process necessary to achieve the colours Alexandrite - referring only to amber, fuchsia and blue  -  there's no mention of uranium or chocolate.
They also show a wine goblet - a surviving shape that seems possibly more common than others.

CH's piece of Alexandrite is a very good photograph, and shows the requisite colours very well.

As far as I can see, Alexandrite is absent from both of Barrie Skelcher's volumes on uranium glass, and unfortunately, the quality of the pic. in Manley is very poor, and his description really too brief.

Would comment again that the alleged piece of 'Alexandrite' which Gulliver includes, has more the appearance of Amberina or equally Rose Amber - the pic quality is good, so can't blame doubts on the image.    Gulliver does give detailed descriptions of several of these heat reactive glass products.....including Alexandrite, which he qualifies as being struck twice "to obtain the change from amber to ruby to violet blue at the rim" - but he makes no mention of uranium or chocolate.   This description of his does seem to go against his own exhibit as being Alexandrite.

The Truitt's 'Bohemian Glass 1880 - 1940 includes several pieces of what appear to be genuine Amberina.

Gulliver and the Grovers are additions to Nigel's comments on sources in the literature, but they don't really add a great deal to the information that Nigel had already detailed.

Just to confuse matters - and as already mentioned by m  -  there have been (or are), other commercial glass products which go under the name of Alexandrite ..........
the Grovers show a transparent pinkish bowl which they attribute as being signed "Moser-Alexandrite",
and in Miller's/McConnell '20th Century Glass' there are items by Heinrich Hussmann for Moser plus ashtrays and sticks from Heinrich Hoffmann.       The Miller's pieces are quoted as dating to c. 1929/30.
All of these C20 pieces are so called, presumably, because of the similarity of the colour to the mineral chrysoberyl.

Apologies to Bernard for digressing excessively - but just thought as we had already detracted miles from his piece I might as well go the whole hog and bore everyone.
I'm sure that Lustrousstone is correct in her description of how the colours of Bernard's piece were combined, and feel there's a good chance that m's comment about the similarity to Grotesque is also near the mark.

If you haven't already fallen asleep - you may now do so.    

[Lustrousstone]

Alexandrite is both uranium and lead crystal. Gulliver's piece is most likely Alexandrite because he does not state as fact something of which he is not 100% sure. That dark rim colouring and seeming lack of much blue is not uncommon

[Paul S.]

your comments may well be correct Christine  -  all I can say is that having looked at a lot of book pix of both Amberina and Rose Amber (States pieces), my opinion is that Mervyn Gulliver's small punch cup appears indistinguishable, in terms of colour, from them - there is some variation within these colour ranges that give rise to doubt.
As you'd imagine, Joseph Locke's original sketch books show that punch cups were included in his repertoire.  Of course, it might be possible to argue that the shell ribbed handle, plus the quilted pattern, was uniquely a T/Webb design, and although Gulliver doesn't comment as such, it's always possible that he has matched his cup precisely with a T/Webb pattern book for Alexandrite.  
 

[flying free]

I’m a bit confused about these statements below.  Is there a reference for these definitions? Nigel was very specific in mentioning the chocolate rim as well as the colours.

‘I was under the impression that if the rim has gone as far as chocolate, the thing has been overcooked during production. They were supposed to stop when it had gone blue.’

and

‘Contrast in the pix is good though, and shows the main deep rose/purple/fuchsia/violet blue signature colours of Alexandrite to good effect, with one piece appearing to show an excess of blue due to over-heating. '            ‘


My piece shows a fine chocolate rim all the way round and whichever way you view the rim, from top, from bottom , looking into the rim edge, whatever.    It isn’t an optical illusion on mine. 



Also is the following statement known to be true?

' As we know, it's the gold in solution, apparently, that is responsible for the Alexandrite colours when re-heated - I wonder if it was 24 ct. - and of course the same ingredient is responsible for the pinks in Burmese. ' 

 I ask this, given that the poster Moultermike says on this thread
http://www.glassmessages.com/index.php/topic,9368.msg210338.html#msg210338
‘This morning I and a student at the university of Kent at Canterbury did some spectroscopy on a Webb's Alexandrite wine glass. I had established previously that the body of the glass was radioactive, so the yellow is caused by uranium. W.W. Weyl in his book "Coloured Glasses" (ISBN 0-900682-06-X), gives three possible ingredients for purple glass; manganese, nickel and titanium. The maximum spectral absorption of the purple in the wine glass was near 575nm, which is consistent with titanium, but not with manganese or nickel. He stresses the difficulty of reducing titanium to the purple (+3) form. However, I suspect that re-heating in a chemically reducing atmosphere, or even covering the edge of the glass with oil and re- heating it, would form purple Ti3+.

I suspect, therefore, that Webb's Alexandrite is based on uranium and titanium, though X-ray fluorescence would be needed to confirm this.’

i.e. I’m asking is it only the gold in the metal that enabled the colours in Alexandrite?


Which leads me onto:


With regards the question over whether the American makers could have just found out that heating twice would have produced the Alexandrite effect seen in Thomas Webb’s Alexandrite - Is it not possible that their glass metal/mix/recipe was in fact not the same as the recipe used at Thomas Webb, therefore they could not just make the same colour effect as seen on Webb’s Alexandrite?  I think it's possible it wasn't because there has been discussion that the Webb Alexandrite is uranium glass whereas the American versions aren't?  I think I've remembered that correctly.  If I have then the metal was made differently which could explain why the versions are different and why they didn't just heat twice to get the same effect.

Paul, with ref your comment (see quote below) on the Alexandrite piece in Gulliver’s  referring to page 256 where he shows a Punch Cup.   I can see the violet in the cup and I think it’s possible there is too much magenta in the photograph for it to be a true representation of the colours of the actual  piece.  Just my opinion though.
But I also agree that Gulliver would not have referred to this as Webb Alexandrite if he did not have proof it was.

‘Would comment again that the alleged piece of 'Alexandrite' which Gulliver includes, has more the appearance of Amberina or equally Rose Amber - the pic quality is good, so can't blame doubts on the image.    Gulliver does give detailed descriptions of several of these heat reactive glass products.....including Alexandrite, which he qualifies as being struck twice "to obtain the change
from amber to ruby to violet blue at the rim" - but he makes no mention of uranium or chocolate.   This description of his does seem to go against his own exhibit as being Alexandrite.’

[flying free]

edited to add to the above:

Just to add to the discussion re the optical illusion v actual colour of chocolate on the rim and dichroicism of the effect, I held my piece very close, right up to, an LED light this evening with the light shining onto it, so I was viewing it with little light coming through i.e. viewing it front on with the light shining onto it from the front  if you see what I mean. 
When I do that the whole top half of my piece goes chocolate 
Viewed with light on it from a distance, i.e. normal diffused lighting it shows all the colours I mentioned previously.

I've seen a picture of the goblet in the Parkington collection (or at least I think it's the one you were referring to) - stunning piece of art.
m