Topic: Opaline glass

[flying free]

On another earlier topic regarding an opaline Etruscan style vase,  there was a many pages long discussion on opaline glass.
The topic of 'what is opaline glass?' appears to arise regularly in discussions.
I thought it might be helpful to give this it's own post, so any addition information or reference sources can be added.

1) The last post I posted on the Etruscan opaline discussion was this one:-



With reference opaline glass and opacifiers in glass:

Chapter 1.2.3.5 of this book has detailed information on the opacifiers used over the centuries.

Modern Methods for Analysing Archaeological and Historical Glass  - editor Koen Janssens


https://books.google.co.uk/books?id=9OunNskEvXYC&printsec=frontcover&dq=modern+methods+for+analysing+archaeological+and+historical+glass&hl=en&sa=X&ved=0ahUKEwjXwJiK7M3MAhVMDsAKHQLLAa0Q6AEIHDAA#v=onepage&q=modern%20methods%20for%20analysing%20archaeological%20and%20historical%20glass&f=false


It explains this process clearly.

You need to scroll down from the top and just keep scrolling until you reach para 1.2.3.5  (being an extract from the book it looks slightly odd scrolling down)

It is an extract from the book so not a link to the entire book.

It falls under the Chapter 1.2.1 - Raw Materials, Recipes and Procedures Used for Glass Making, (Cesare Moretti and Sandro Hreglich)

[flying free]

2) here is another reference source of information regarding information on 'girasol glass':

Source reference and quote  for my comment on girasol glass being opaline - here on the Museo del Vetro website under the heading of Opal Glass
http://museovetro.visitmuve.it/en/il-museo/percorsi-e-collezioni/the-arsenale/the-arsenale/

'Opal glass (Girasol or Sunflower). Opalescent glass with an orange sheen, more matt than opaline, introduced into Murano technology since 1693. This glass is slightly opaque due to the presence of lead hydrogen arsenate crystals in the glassmaking mixture, that due to their size confer an original colour to the glass, which appears bluish when observed under reflected light and light brown, or pink, when observed under direct light. In the 1800s, this type of glass was presented by Salviati & C. at the Industrial Exhibition at the Doges’ Palace in Venice. On that occasion abbot Vincenzo Zanetti wrote “Opaline glass, which after repeated and very expensive experiments was finally obtained in Salviati’s laboratories due to work on glassblowing in all security and a very beautiful quality, was one of the most reluctant to mingle with other colours. In our opinion it must have been so also in the past, as it is true that the ancients knew very well how to produce the lovely opaline paste and wrought objects of diverse forms, but such objects of past ages, which are not found profusely and that are therefore paid fantastic prices, are not pure, meaning without other colours. Well, Salviati was the first to show us this lovely glass merged and decorated with any other paste and even with ruby and with aventurine itself. …” (La Voce di Murano, 18 July 1868, N°. 28, pages 117-119).'




3) and a good article here on the Roland Dufrenne site which explains the transition from transparent opaline with opalescence to the less transparent over time - the  period mentioned being 1820-1860.  The pictures speak for themselves and the first picture is clickable so it can be enlarged to show how translucent the early opaline was as well as the opalescence on it.
http://www.rolanddufrenne.com/les-opalines/

Using google translate the translation of the article reads as follows:

'Originally, in ancient times, glass was opaque. From a close look of porcelain, it was used in imitation of some precious stones.
From the fifteenth or early sixteenth century Venetian glassmakers produced a white opaque glass called lattimo inspired the porcelain of the Far East which the method was unknown in Europe.
This glass was obtained by the addition of lime and tin composition.
In the early nineteenth century, appears crystal opal or opaline crystal, more or less transparent, milky appearance soap or obtained by the addition of phosphate of lime (calcined bones).
The crystal created in the second half of the eighteenth century, Vonèche, St. Louis and Montcenis, be the first to make crystal opal, but the first half of the nineteenth century saw the creation of more high-quality crystal, including the crystal Choisy-le-Roi (1820), Bercy (1826), Lyon-Guillotière (circa 1839) and Clichy (1842). The first two produce most of the beautiful opal crystal opal we now call Restoration period or Charles X. The opaline crystal comes in several pastel colors: lavender, turquoise, pink "pigeon-throat", ultramarine blue, amber and green jade.

Glass of water opaline blue (1850)
In 1844 began production of opaque glass with vivid colors (blue flag, green chrysoprase, pink, lemon yellow) plus a semi-opaque white, slightly gray, called "rice paste" or "alabaster" such opaque glass produced by all the major crystal under the Second Empire, is now known as opaline, name and adopted by the widespread trade in antiquities in the early twentieth century.
Manufacture of opal with bright colors reached its peak between 1850 and 1860, it decreased significantly at the end of the Second Empire'






4) Research article and documentation  on the making of opaque Venetian glass 15thc to 20thc and the use of opacifiers/which opacifiers were used when. 
I've used an automatic translator - it should allow you to click the translate box at the top and do an automatic translation
'Les verres opaques :la technologie des verriers vénitiens (XVe-XXe siècle)'
Authors:

Cesare MORETTI ,
Chemist, Technologist Verrier
S.Vito al Tagliamento (Italy)

Sandro HREGLICH
Researcher
Stazione Sperimentale del Vetro, Venice (Italy)

http://www.verre-histoire.org/colloques/innovations/pages/p202_01_moretti.html

(Note - I think no 4) might be the research, or linked to the research, used in the book in point 1)  - it is the same authors )

[flying free]

just cross referencing to this thread where there is further discussion ongoing regarding the use of the word 'opaline' as a descriptor:

http://www.glassmessages.com/index.php/topic,65793.msg367967.html#msg367967

[flying free]

ok, re the use of the word 'opaline' -

I suggest as reading material
Edith Mannoni, Opalines, Paris 1974.

Having read an extract it gives a good explanation and history of French Opaline glass.

m

[flying free]

I have copied this information from the other thread because I think it's an important source in the discussion of the use of the word opaline.



In this report of 1862 from the Annales du Conservatoire National des Arts et Metiers
on page 536 under the paragraph headed 'Verre Opale',
the description describes how the glass becomes quote 'opalines'.

Quote:
'Verre opale -  Le verre fondue est transparent;  c'est en rechauffant et en faconnant les pieces quelle deviennent opalines'

Translation (google translate):
Opal glass - The melted glass is transparent; it is by warming up and shaping the pieces that become opalines



That report also has a paragraph entitled 'Verre de Albatre' just above the paragraph entitled 'Verre opale'. I believe  this translates as 'Alabaster glass' and it seems they are describing the French 'pate de riz' . I have not translated that paragraph.


Source:
https://books.google.co.uk/books?id=CPA0AAAAMAAJ&printsec=frontcover&dq=Conservatoire+National+des+Arts+et+M%C3%AAtiers&hl=en&sa=X&ved=0ahUKEwiej6q0wpXXAhUDuhoKHYWmBOw4ChDoAQhLMAc#v=onepage&q=Verre&f=false

So a description of glass from 1862 using the word 'opalines' as a descriptor.
m

[Anne Tique]

The thing with the french language, and therefor the french but I don't mean this in a criticizing way, is that like many languages it constantly evolves, new words come and go, like anywhere else, Dutch is very similar in that way. I sometimes read the news and come across new words, and I have no idea what we're talking about.

What I have always appreciated though, is that the french always have this particular way of expressing themselves, and especially in the old days, they expressed themselves extremely poetically, and it still happens today, perhaps a bit less romantic, but it's not unusual to hear or read a bunch of words, that say very little or nothing at all. When I'm reading, for instance a report on a worldexhibition, in which items are described, it's almost as if you've gone to heaven, and the most amazing and incredible expressions are used to describe an item or a technique, and it's beautiful ... call me old-fashioned.

I therefor think, that any older descriptions in french, no matter what it is, should not be taken too literally, as especially in the old days, this was a way to report news and make people dream, wonder or fascinate the general public. I 'm not referring to your last post M, but it's just something I have observed throughout the years.   

[flying free]

 


 I'm just adding it as a possible source of where the word opaline as a descriptor might have derived.

Mannoni mentioned early 1900s - I think it might have been earlier.

Possibly all deriving from the apparent Baccarat invention of the word 'opalin' for their range of .. not transparent, not opaque glass mixed in the batch.

I am very curious to see an original source of this Baccarat word 'opalin'.  Does anyone have one?

m

[Anne Tique]

I've only added my bit as a general observation, not referring to anything or anyone else besides the french and their language. 

[flying free]

oh yes, but I come across the same problem with the Art Journal of 1851 descriptions of the British Glass in the Great Exhibition 1851.

On reading some of the reports, the writers are sometimes scathing about glass that isn't transparent and cut. 
I've seen horrible descriptions of the gorgeous Bohemian glass exhibited there - e.g.  too colourful, too much decoration etc etc, where as our wonderful British glass ... well 

Then in the next breath they are commenting on how the British glass is now very colourful and has overtaken Bohemian glass in it's beauty.  I might call this 'bigging up' 

Very subjective writing!  and not romantic and positive like the French.  It reads as a great piece of PR for British glass - extremely subjective and opinionated.  And some most of the British writing that I have read (not exhaustive) appears to me to show a distinct lack of knowledge of the difficulties involved in the  processes of making glass, casing glass, and decorating glass in that period.

Obviously that is only my opinion and is an extreme generalisation.  But there is a common 'theme' there it appears to me.

[Anne Tique]

I've just read this in a french book on Baccarat.

" in 1823, when Pierre-Antoine Godard-Desmarest (read this name before in one of the Google book links you posted) and his associates restart the cristallerie (Baccarat), the only coloured pieces, from the Fantasy range, were realized in cristal 'opale', called thus due to its resemblance of the opal stone. Characterized by its milky white aspect, more or less opaque, extremely soft to the touch, this crystal reveals an orange, transparent glow once it's held against the light. The process to obtain this effect was already known in the time of the venetians, and it consist of adding phosphates from ashes and powdered bones. Once out of the heat, a reaction appears : the crystal, once gathered becomes opaque while it's been worked on. The more it's reheated and cooled down, the whiter it becomes. It comes down to the dosage of the phosphates and the time that it's worked on to give it the desired effect. The 'golden period' of opalin crystal, marked by very large vases on which the decors were painted by decorators from the Sèvres porcelaine company, started in 1845 to be terminated in 1860 (I presume this refers to the production of cristal opale at Baccarat)."

So the process was already known before Baccarat, but nothing from this quote confirms that the name did too, unfortunately.