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Glass Discussion & Research. NO IDENTIFICATION REQUESTS here please. => British & Irish Glass => Topic started by: Paul S. on December 03, 2021, 07:02:04 PM
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I thought it would now work, but not letting me add pix - so all you get is words. Will keep trying - sorry.
Opaline is a complex subject, as we've discovered before - so will try to keep this one simple ........................... 'Vitrified' opaline was patented (in the U.K.) by Richardson's some time around mid 1840s, I think - apparently opaline was a new invention for them, involving adding a flux to the metal oxides and sand and opacified with ashes of calcined bones - the flux apparently achieves a lower melt temperature .......... how this compared to the Continental opaline - form Baccarat for example I've no idea - please add if you know :) 'Vitrified' means to convert something into glass or to make glass-like, and calcined means - I think - that you've reduced a substance to the bare bones - (literally in this case). Opaline has a translucent appearance, and produces the well known sunset glow, and there are some v. famous coloured versions ... gorge-de-pigeon (pigeon's neck) and bulle de savon (soap bubble rainbow hues) for example - these are just plain white.
Neither of these pieces carries a diamond lozenge, though apparently some examples do - as can be seen, one base carries a pattern No. of P 323 - the other base shows only the upper case P but lacks the No. - most similar Richardson opaline pieces showing typical Grecian/Etruscan pix date to c. 1847 - 1848. The pattern No. may refer to the shape of the vase or equally to the design image of the transfer - really not sure.
There is an almost identical vase - matching one of these - showing in Hajdamach's 'British Glass 1800 - 1914' - page 101, colour plate 9 - showing sepia transfer decoration, though unfortunately there's an absence of any indication of height. - these two weigh in at 8.25 inches (c. 21 cm.) Most of this information comes from Hajdamach and Gulliver, and if you don't have these, you should - well worth the money.
Anyway, one of the bigger surprises of recent times, and not a fleabite in sight though some of the gilding on the high spots has been worn. Plenty of wear, but I sense these have likely been in Granny's cabinet for quite some time. One picture will flip to the following post.
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Correction to the following sentence:
Quote from Paul ' Opaline has a translucent appearance, and produces the well known sunset glow, ...'
Opaline glass does not always produce the well known sunset glow. It can also be made without this glow.
I think I have got to the bottom at some point of what might cause opaline glass to glow or not (will try and find source and link). It appears in glass made with bone ash but I actually think it's lead arsenate crystals (??) that produce the glow.
Opaline glass made without this glow can be known as 'alabasterglas', e.g. pertaining to glass from Bohemia, and was made for example at Sklarna Annin (Annathal bei Schuttenhofen) in the 1830/40s and I think also the factory Adolfhutte bei Winterberg. That is also opaline glass but it does not glow. It's made with a different composition. I think containing tin oxide.
I do have a source for this information about the opalescent glass that contains (?)Lead arsenate(?) . I will try and find it.
In Venetian glass of the 16th and 17th century this opaline glass with the sunset glow was known as Girasol glass
Opaline glass with the sunset glow is known as opalescent glass but it is still opaline glass.
Opaline glass can appear without this glow dependent on it's chemical constituents.
Opalescent glass can also be made by the way the batch is made up and then the subsequent way it is cooled.
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look - I really do refuse to rise to the bait and join your discussions about opal, opaline and opalescent ;D ;D :-* seriously, I'm sure with the time you've spent reading up on this stuff you must know shed loads more than me. I'll go away and try again to upload the pix.
sorry, still no good. Perhaps if I can send the pix to Anne, that might be a way of circumventing the problem - it's still coming up error 403 and telling me I don't have permission to access this site.
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I have read a better source for this - more explanatory, but anyway here is a link to a statement on a page from
Museu Nacional d'art de Catalunya
'Opacifier
A chemical compound that is added to the composition of glass enamel to make it opaque. Various different opacifiers have been used over the centuries, such as calcium antimonate, tin oxide or lead arsenate.'
https://www.museunacional.cat/en/opacifier
White opaline jug attached to test picture attachment for you - Bohemian c.1850 Neuwelt, not opalescent, no glow.
White dolphin jug Salviati c.1870 opaline and opalescent. Just looks white opaline in daylight with light from front (with a slight blue hint but it is white). I don't have a photo of it lit like that unfortunately. Under lighting glows bright orange as it's opalescent.
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hmm ......
1 .............. as to opacifiers, I'm at a loss to understand why your link omits any reference to ashes of calcined bones which appears to have been the standard ingredient used over longish period as prime opacifier for these 'opal' products. Probably, like many modern solutions to impractical or archaic processes, chemicals have taken the place of antique practices - perhaps getting hold of ashes of calcined bones is now difficult.
2 ............ re the Neuwelt jug - your image shows the jug with reflected light only - the sunset glow is normally a feature of transmitted light - i.e. seen when the glass is held up to a strong light which has penetrated the glass. Whilst I'm not going to argue with you, I'd suggest that as an example of a test for sunset glow/opalescence, using reflected light is the wrong method.
3 ............ the Salviati jug is v.g. - he seems to have had a thing about opalescent -- not sure of the ingredient that causes this one to 'glow bright orange - is this colour the result of using one of the metallic oxides perhaps? When you say 'under lighting', are we talking transmitted light from a fluorescent tube? I have a Salviati wine that produces a sunset glow, and as you say, his material does often appear with a faint bluish tint in ordinary light.
4 ........... now going for breakfast.
P.S. how about I send the pix to you as a pm, and you might try for me ?
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ok. Calcium phosphate - Bone ash as I understand it was also used as an opacifier, I don't know why they omitted it.
This attached document is explanatory and the source is impeccable.
See attached link:
https://www.istitutoveneto.org/pdf/testi/vetro/2013_03_verita.pdf
Page 59 under the section Lattimo
and page 60 under the section Girasole
Source: Marco Verità*,
'Secrets and innovations of Venetian glass
between the 15th and the 17th centuries:
Raw materials, glass melting and artefacts'
-The first jug in my post above is shown lit by a strong lamp. It is white opaline. I know of what I speak and it has absolutely no 'red/orange/fire glow' under bright sunshine or any other strong light source, neither 'old fashioned' bulb, led or fluorescent. It's opaline glass.
-The second jug in my post above is also white opaline. It's thinner in appearance by comparison to above jug. It has a strange faintly blue glow to it but is most definitely white. However under strong sunlight/'old fashioned' bulb light it turns orange.
- As I read it, in the last third of the 1800s Salviati 're-invented' girasole glass that had been made in the 1500/1600s/early 1700s. I think, from my reading, that the knowledge must have been 'lost' between then and Salviati's work ... or fallen out of fashion. Venetian glass popularity was on the wane it seems during that time. English lead glass became the 'thing' and then Bohemian glass was in the ascendancy.
- I also have an ancient piece of Venetian opaline glass from late 1600s(possibly up to 1707) which is an example of the Girasole glass described in the recipes of the 1600s and early 1700s mentioned in the attached document. It is blue opaline (definitely blue not remotely white). Under strong light it turns bright orange and when the light is directly behind it, it turns clear transparent.
It is early Girasole glass exactly as described in the attached document on page 60.
So I can do a direct comparison between that and the two centuries apart Salviati piece. They both turn orange under sunlight/'old fashioned' light bulb.
-I have bleu lavande coloured pieces of glass from Bohemia and France dating to very early 1800s. They turn red under sunlight. They don't go clear under strong light. They are a much darker blue. The French piece is very translucent, the Bohemian almost opaque but turns bright red at the rim (thinner part, more easy to transmit light through) when held up to strong light.
Feel free to send pics to me and I'll resize and try and upload for you.
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thanks for the information - much appreciated.
I've already re-sized the pix (one of the few techie things I can do), and they're now 900 x 675 which is a size I can usually post (sometimes it's 675 x 900 or slightly less - depends on whether I'm shooting with the camera oriented to landscape or portrait).
If you feel there's a need then perhaps taking them down to 750 x 500 might possibly improve things, but I've just tried again and the same problems exist.
Will try to send later this morning, and thanks for the offer.
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An interesting footnote from the book ' PITTSBURGH GLASS ' by Lowell Innes concerning English opal.
"An undated English catalogue [ca. 1870] ostensibly prepared for manufacturers gives twenty-two formulas for opal. Arsenic appears in every one in amounts from 6 ounces to12 pounds, an average being about 4 pounds. Thirteen other formulas are called white enamel".
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thanks - I'm not surprised at this multitude of recipes for 'opal' - an association word that carries with it many of the qualities and attributes of the real thing - it seems to have been a fashionable description for so many glass inventions over the past couple of centuries, to include the word opal. As to the C19 recipes for 'opalescent' glass, I'm unsure as to the extent of the arsenic content as an opacifier, or as a means of contributing to the 'opal' effect i.e. the sunset sparkle - much of the literature is unclear on this - possibly some of each. Generally, with these C19 products, and for obvious reasons, glass houses were no doubt reluctant to publish details of what went into their pots.
In the U.K., John George Sowerby was responsible for the invention Vitro-Porcelain, and the first colour they produced was a plain white which they called 'opal' (it's a truly opaque material with the appearance of a milk-white opal, so no chance of transmitted light). I don't see that the ingredients included arsenic, but can't be sure - the main content appears to have been cryolite plus some oxide of zinc and the sand - no mention of ashes of calcined bones.
A little later with his Patent Queen's Ivory Ware, he speaks of "adding to the usual ingredients of common flint glass, arsenic to make the glass opaque, and as we know, he also added uranium to the Ivory batch "to give it the yellow tint". However, Sowerby appears not to have been happy with this recipe, and later he speaks of improving the appearance of 'Ivory' by dispensing with arsenic and substituting cryolite spar, plus some other ingredients - the u. was of course retained.
So, as with 'Vitro-Porcelain, the main opacifier for Ivory, appears to have been cryolite, since there isn't any mention of arsenic or ashes of calcined bones in the final recipe - again, as we know, Ivory is a fully opaque product, and no chance of any sunset glow with opque products.
Sowerby continued with his inventiveness and produced Blanc-de-Lait, about which the Pottery Gazette said ..................... "Three years have been spent in experiments on the opalescent product by Mr. Sowerby etc. etc. ......." it's a mostly translucent glass and according to one observer ............. "Held up to the light (transmitted light), it shone like opal in a hundred delicate hues, chief amongst which was a glowing yet tawny gold, that suggested the sun shining through a purple mist in evening. "
Unfortunately, I can't see the recipe for Blanc-de-Lait - the opacifier may have been arsenic and there may have been ashes of calcined bones added too.
Someone else said of Blanc-de-Lait .......... "it was of a rich, lustrous, milky colour, verging in the thinner portions into that sky-blue which milk assumes when it's vendor has had dealings with 'the cow with the iron tail'" .......................... so might it be lead arsenate or cobalt that gives this bluish hue - with Jobling, much later, it was the inclusion of cobalt.
Other than Sowerby, Ray Slack mentions Edward Moore & Co (U.K.) who used calcined oats; or, other calcined cereal; or, vine stalks as ingredients in the opaque batch - Edward Moore (in Slack) gives an account of his recipes for 'Eau de Nil (soft opaque green (probably nothing like the Nile), and a type of 'caramel brown'. Moore appears to be saying that he adds these calcined cereals as colouring substances.
Coming forward some decades - and without getting too bogged down in chemistry - but just to show perhaps a more modern take on this issue of opal/opalescence etc. Jobling produced a very well known product called 'Opalique', the idea for which appears to have had its origins in their lighting bowls - similar to the Chance panels and of course to the famous opalescent products of Lalique in France. Jobling's translucent light bowls were opacified using phosphate, fluorine and alumina - so no ashes of calcined bones - but amongst a very varied bunch of ingredients they experimented with was white arsenic - plus they included a trace of cobalt which "was successful in producing an attractive blue glass with an inner golden fire (sunset glow), similar to that found in some Lalique products.
"The density of the opalescence depended on the rate of cooling of the outside relative to the centre: the opal within cooled more slowly, allowing crystals to form which refracted the light."
Much of the above is taken from the original research work of Ray Slack and of course Baker & Crowe re the Jobling material published in the Tyne & Wear County Council Museums Collectors Guide - and much credit to these authors that their work is publicly available for all of us to read - I just do the typing plus the italic bits. If you've not seen the Baker & Crowe publication it really is worth getting.
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Paul, under the section Girasole in the document I linked to above it gives the following information on the source of the opalescence:
Quote:
'The opalescence is given by very small microcrystals of lead
arsenate [3Pb3(AsO4)2PbO] which separate during melt cooling
(light scattering). The intensity of this phenomenon depends
on arsenic and lead concentrations and on melting and cooling
procedures (sizes and concentration of the particles)'
Apologies - I'm embarrassed that I've been unable to type the formula quote exactly - but in the formula quote above the 2nd no 3, the no4 and the no2 are given as tiny numbers at the bottom - If any mods are reading and can change the formula as I've written it above then that would be great as obviously how I've typed it gives an incorrect formula.
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trying to link your picture on the main Glass thread - ok that worked so at least there is a picture attached now :)
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thanks for the formula etc. - I doubt that I'd know remotely whether it was correct or not - but at least it appears that we're both speaking about lead arsenate - plus some arsenic - as being responsible for the colour under transmitted light.
thanks for adding a copy of the original image showing the two Richardson vases, to this thread.
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Have you tried contacting the mods through the 'report' button Paul?
They should be able to help you upload pics to the original post.
m
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Concerning cryolite , this also comes up in the aforementioned book 'PITTSBURGH GLASS'. As follows.
""J. Stanley Brothers identifies one such change by the use of cryolite [alumina] to increase the translucence of American opaque white. In speaking of early overlay he says: "The platings of subsequent specimens secured their opacity from the use of the mineral [cryolite]; the softer texture of earlier glass gave way to the 'vitreous appearance of later ware."* By the seventies alumina was hailed in America as making as great a revolution in opaque white as petroleum had made in lighting.""
*A seeming contradiction: cryolite to increase the translucence and also to strengthen the opacity.
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I don't understand it either - will have to mull over for a day or two though likely the meaning will remain elusive. Can you clarify a little what is meant by the expression 'the platings'. thanks.
re the pix for the vases m, I'll have another go tomorrow, and failing that will try to contact Anne (Mod.)
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I think it another term for 'overlay'. Inness in his book states that the term overlay is/[was?] used mostly by Continental and American factories. The process of casing being a more involved process.
The goblet pictured could well be termed overlayed in white on clear. In fact it may be a specimen of exactly what J. Stanly Brothers is talking about. There is no "fire" in the white "plating" and a certain translucence at the thinner areas.
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yes, think you're probably correct - it sounds to be a a common sense expression equivalent to 'overlay'. Don't know about your side of the pond, but Europeans would be likely refer to a piece with this appearance as 'cut to clear'. The traditional means of making drinking glasses with shapes similar to this is by means of a three part construction - bowl, stem and foot - it's possible here that the clear bowl was cased/overlaid with the opaque colour, before being attached to a clear stem, and finally the overlaid foot attached. But I'm speculating of course, though to overlay a bowl once it's attached to stem and foot would be more difficult.
With the glass in its completed form the bowl is then 'cut to clear' - a decorative technique I'm sure seen more commonly on the Continent of Europe (particularly Bohemia), rather than within the U.K., though it was a process used everywhere.
Nice pieces if they're all yours. This doesn't solve the other contradiction of translucence versus opacity - and we may never resolve that one (from the book).
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In Bohemian glass, this technique of three layers - ( in Cagney's example is it just one colour white over clear though? It looks like two layers in the photo) - is known as Doppelüberfang - or double overlay i.e. double overlay on top of the clear.
A single overlay is known as überfang.
Two layers on top of a third were very difficult. The annealing process had to be correct along with the rates of cooling of the colours of the glass, otherwise it cracked. That was the problem they had with reproducing (the English version) of the Portland vase in the 19th century. Franz Paul Zach engraved two versions of his Portland vase. One is in the Corning.
The Bohemians were masters of Doppelüberfang. It does seems as though Bacchus also produced a white on red (and possibly those two over a clear base?) in c.1849. A decanter example is in the V&A.
If I was researching the goblet I'd be looking at French to start. Is it French?
I know it as overlay glass or cased glass if thinking about any cased glass other than Bohemian/German however I think the French have a specific term for it as well. I just can't remember it at the moment.
Casing was achieved in various methods. Charles Hajdamach's British Glass books have details on how this might have been done.
I should think every maker had their own recipe for white opaline glass. This was also referred to as 'opal glass' in the mid 19th in England as far as I can work out from contemporary reports of the day. It's still opaline glass. It just had the name 'opal glass'.
m
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The goblet is an imperfect piece and hard to say where made. The clear part is lead glass [short wave U.V.]. The auction house I sold it through in 2010 decribed it as " lady's goblet 5 3/8 in. tall. American or European ca. 1870-1900.
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I think that's definitely French, Cagney.
Best to put on it's own thread though to discuss.
m
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In Baguiers et Verres a Boire, Leon Darnis, on page 165 there is a goblet from Clichy. I think it has the same star cut and overlay foot but it's blue.
Also page 160 and 161 shows 4 items with white overlay. Similar feel and style to yours. Different makers but they are all graphic design white overlay on clear.
One is from Clichy with a similar star cut foot and white overlay on that one. The design of the overlay is also spare and graphic but different to yours. The stems on all of these is a different design to yours. They date from c.1840/50.
Oh ... Stem design match for your goblet on page 172 of book a goblet from Saint Louis. From that then,also a goblet,with star cut overlay foot but in blue and the star has many more points than yours. The design of the overlay is like yours but many more arches.
That said,none of the 4 white overlay versions shown are from Saint Louis.
If you have a UV light what colour does the clear glass give off under that? Is it an orangey salmon tint or yellow?
Looking through the Clichy book, a similar stem design but the way it's applied to the foot is different. That could be because the foot on that bowl is cupped upward though. Page 313.
m
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Wether American or European the goblet no longer in my possession. Sold all the better glass in my collection back in 2010. That financial crisis back then. I did archive them in digital photos. The goblet did test positive for lead under shortwave UV.
One recurring problem with attribution of American glassware of the finer type in the first half of the 19th century other than pressed glass is the influence of English,French and sometimes German workmen induced to immigrate by the glass companies. Thomas Pears of Bakewell made several trips to England and the continent to find [pilfer?] skilled workmen even tho it was illegal to do so at the time in England. He would also acquire examples of glassware in the newest fashion.
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Ah, ok, I'll stop noticing similar items then :)
The 'acquiring' of fashionable glass I think is/would have been quite normal. It's important to see what the competition is doing and to be able to make comparable items if so desired.
Also, in the days where competitively priced glass was being imported from other countries and there was a local industry that could compete in manufacturing terms, I can imagine that having examples in order to produce locally in whatever country, would have been seen as a necessity.
I've seen and read some odd things in older literature about glass being found at a makers site or in a family collection,or from the collection of said maker - now knowing that the carefully treasured glass has turned out to be Bohemian/French or by another maker.