Topic: Small facet cut stem ruby glass - Gorge de pigeon / Gold-ruby instead

[flying free]

I also think this book raises an interesting point:

Gold Nanoparticles for Physics, Chemistry and Biology  (2012)
By Catherine Louis, Olivier Pluchery

Page 14 chapter 1.2.4.2

'How Kunckel managed to produce gold ruby glass on such a large scale remains a mystery.  Moreover, although some vessels can be dated to a period where Kunckel might have been the glassmaker (Fig.1.2.), none of them can be unambiguously attributed to him (source: page 123 Glass of the Alchemists)


https://books.google.co.uk/books?id=2c-6CgAAQBAJ&pg=PA27&dq=glass+of+the+alchemists&hl=en&sa=X&ved=0ahUKEwiLsqX8_8XMAhVCL8AKHdlRDKsQ6AEIJTAA#v=onepage&q=ruby%20glass&f=false

[Ivo]

I will email you when I get back to my research notes. Until then, I think that ruby the colour is not to be confused with goldruby the process. It is not just dealers and curators who use the term loosely, it is also people who should know better like cmog. And let's not obfuscate the matter with other glass types which may or may not be related. This may be a multiple and complicated misunderstanding. Any testing method for gold content would be a destructive one.

[oldglassman]

HI ,
          I did say that I would probably have nothing further to say on this thread through lack of personal knowledge on the subject , but I do have the book and can tell you that these words

"How Kunckel managed to produce gold ruby glass on such a large scale remains a mystery.  Moreover, although some vessels can be dated to a period where Kunckel might have been the glassmaker (Fig.1.2.), none of them can be unambiguously attributed to him (source: page 123 Glass of the Alchemists)"

are not on page 123 or in any of the 10 pages of text on the subject,

cheers ,

Peter.

[flying free]

          I did say that I would probably have nothing further to say on this thread through lack of personal knowledge on the subject , but I do have the book and can tell you that these words

"How Kunckel managed to produce gold ruby glass on such a large scale remains a mystery.  Moreover, although some vessels can be dated to a period where Kunckel might have been the glassmaker (Fig.1.2.), none of them can be unambiguously attributed to him (source: page 123 Glass of the Alchemists)"

are not on page 123 or in any of the 10 pages of text on the subject,

 

Thank you.  As can be seen from the link, that was their reference source.  So a poor reference for me to link to.
As a matter of interest is there a reference in Glass of the Alchemists that does 'unambiguously attribute' them to Kunckel?

Until then, I think that ruby the colour is not to be confused with goldruby the process. It is not just dealers and curators who use the term loosely, it is also people who should know better like cmog. And let's not obfuscate the matter with other glass types which may or may not be related. This may be a multiple and complicated misunderstanding. Any testing method for gold content would be a destructive one.

I understand. I thought I had learnt something about another old opaline piece of mine.  I do now wonder.

m

[oldglassman]

Hi ,
           All items mentioned  (22 vessels) with some illustrated are attributed to Brandenburg pre 1690,there are a lot of surviving period documents (between Kunckel and his patron) that discuss the items Kunckel was making ,a peculiarity with his productions seems to be the weight of the objects with 1 very well documented though now lost goblet weighing 24 pounds , so I imagine weight would also be  another factor used for attributing a glass from that period,

"How Kunckel managed to produce gold ruby glass on such a large scale remains a mystery.

I wonder if what this really means is objects of large scale ? which would fit with the 24 pound 1 mentioned or scale as in quantity,22 attributable items today doesn't suggest production on a large scale , just a thought.



so not a 100% Kunckel without a doubt ticket, 99.999 % attributions with supporting evidence which is not surprising when dealing with unsigned pieces

cheers ,

Peter.

[flying free]

Thank you Peter.
I have read about the 24 lb weight goblet.  I think I read it was made in three pieces?

I wonder how many people helped Kunckel make that goblet?  Handling even an 8lb piece of glass(24lb goblet made in three pieces I thought so I just divided 24lb by 3 pieces to get an average weight for each piece) and getting that gold ruby colour perfect through the right temperature must have been difficult I would have thought? 





This blog entry was posted by Paul Engle on 17 February 2016

http://www.conciatore.org/2016/02/gold-ruby-glass.html

It makes very interesting reading. I have quoted a part of it - please see the blog for the full article

Paul Engle translated L'Arte Vetraria
http://www.amazon.com/LArte-Vetraria-Antonio-Translated-Annotated/dp/0974352934

There is a link here on the Corning Website to that blog
http://www.cmog.org/article/antonio-neri-alchemist-glassmaker-priest



'Doubts about Neri's gold ruby glass recipe grew after his death, when it was discovered by other experimenters that the addition of small amounts of tin into the mix produced the ruby color quickly and reliably. This compound of tin and gold chloride was called "Cassius purple" after one of its inventors and its color. In some circles it was thought that the tin was an essential ingredient, a lost secret that had been rediscovered. The argument was that gold chloride alone could not produce the color, it must be combined with tin in the form of Cassius purple. However, this is not the case.

In an 1846 edition of the Journal of the Franklin Institute (ser. 3, v. 11), professor of chemistry and natural philosophy, E. L. Schubarth, cites numerous investigators who demolish this theory. He wrote:

"It must not be imagined from this, as some persons have lately stated, that it is necessary to use gold [combined with tin] in the state of Cassius purple.

Neri, at the end of the sixteenth and commencement of the seventeenth century, stated, that in order to stain glass a ruby color, it was only necessary to employ calcined chloride of gold. At a later period, Libar wrote to the same effect, and Merret certified that he had proved the efficacy of the process. In 1834 Golfier Besseyre stated, in the Journal of Pharmacy, that Douault Wieland colored his paste with perchloride of gold only. Lastly, in 1836, Fuss writes, that in Bohemia all the ruby-colored glass was prepared with chloride of gold only, and that glass might be stained red as well with metallic gold, as with oxide of gold or Cassius purple.

It is therefore a fact known for some time, that glass may be stained red, without either Cassius purple or oxide of tin, with [only] metallic gold or preparations of gold. In the glass-works of Bohemia and Silesia perchloride of gold only is used, without the addition of oxide of tin, in order to produce their fine rose or carmine-colored glass."'

[oldglassman]

Hi ,
       In Glass of the Alchemists Neri and his "L'Arte vetraria" is discussed at length in relation to Kunckel , " Kunckel commented on the outcome of every one of Neri's recipes,having tested them all himself "

cheers ,

Peter.

edited to add , the book is readily available from several on line sellers and by today's standards for such a large book covering many subjects with lavish illustrations I don't think it is expensive  around £25 should get a copy

[flying free]

yes I have read that comment about Kunckel testing the recipes.




I was interested to read this though

'Doubts about Neri's gold ruby glass recipe grew after his death, when it was discovered by other experimenters that the addition of small amounts of tin into the mix produced the ruby color quickly and reliably. This compound of tin and gold chloride was called "Cassius purple" after one of its inventors and its color. In some circles it was thought that the tin was an essential ingredient, a lost secret that had been rediscovered. The argument was that gold chloride alone could not produce the color, it must be combined with tin in the form of Cassius purple. However, this is not the case.

In an 1846 edition of the Journal of the Franklin Institute (ser. 3, v. 11), professor of chemistry and natural philosophy, E. L. Schubarth, cites numerous investigators who demolish this theory. He wrote:

"It must not be imagined from this, as some persons have lately stated, that it is necessary to use gold [combined with tin] in the state of Cassius purple.

Neri, at the end of the sixteenth and commencement of the seventeenth century, stated, that in order to stain glass a ruby color, it was only necessary to employ calcined chloride of gold. At a later period, Libar wrote to the same effect, and Merret certified that he had proved the efficacy of the process. In 1834 Golfier Besseyre stated, in the Journal of Pharmacy, that Douault Wieland colored his paste with perchloride of gold only. Lastly, in 1836, Fuss writes, that in Bohemia all the ruby-colored glass was prepared with chloride of gold only, and that glass might be stained red as well with metallic gold, as with oxide of gold or Cassius purple.

It is therefore a fact known for some time, that glass may be stained red, without either Cassius purple or oxide of tin, with [only] metallic gold or preparations of gold. In the glass-works of Bohemia and Silesia perchloride of gold only is used, without the addition of oxide of tin, in order to produce their fine rose or carmine-colored glass."'

It's interesting to me because I'm still curious as to the date of my glass and as to how they managed to make the colour so beautiful if it is coloured in the mass and is copper ruby glass. 
From what I read (do not quote me please) it seems that copper ruby was often cased over clear glass as otherwise it was way too dark.
It appears to me, to be quite difficult to find first half 19th century red glass coloured in the mass.

[oldglassman]

Hi
 " I wonder how many people helped Kunckel make that goblet?  Handling even an 8lb piece of glass(24lb goblet made in three pieces I thought so I just divided 24lb by 3 pieces to get an average weight for each piece) and getting that gold ruby colour perfect through the right temperature must have been difficult I would have thought? "

I dont think that question has been answered by anyone , though it is said that Kunckel was responsible for both the chemistry and the glassblowing himself , it also comments that his first attempts to make this huge goblet were unsuccessful due to an incorrect translation of Neri and due to the huge size of the piece which apparently had 1 ins thick walls as requested by his patron who had instructed Kunckel to make red glass no matter what time or cost it took,

from your post above

"Neri, at the end of the sixteenth and commencement of the seventeenth century, stated, that in order to stain glass a ruby color, it was only necessary to employ calcined chloride of gold.

also form G of th A

 " Sixteen of the 133 chapters in Neri are devoted to red glass,9 of these offer formulas that produce a more violet or brown colour and these are based on the use of manganese, six formulas employ copper, and 1 recipe mentions the use of gold."
 "Neri's recipe apparently works (it was tested under ideal conditions in 1930) Kunckle's attempts though to reproduce the recipe did not succeed,misled by an incorrect translation of neri's work.",,,,,,,,,,,,,  and a lot more information follows

 cheers ,

Peter.

[flying free]

yes the Corning article says that Kunckel claimed he made it himself:
http://www.cmog.org/article/gold-ruby-glass


I may get this book but it's very expensive.  Might have to be a birthday present.
However, it might have information in on another piece I have.

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


Source: Modern Methods for Analysing Archaeological and Historical Glass
edited by Koen H. A. Janssens
Edition first published 2013

Re my comment here

It's interesting to me because I'm still curious as to the date of my glass and as to how they managed to make the colour so beautiful if it is coloured in the mass and is copper ruby glass. 
From what I read (do not quote me please) it seems that copper ruby was often cased over clear glass as otherwise it was way too dark.

Perhaps mine is cased somehow -  I have a spa beaker with handle that is red cased.  But that has a clear engraved panel on it and a clear base so it's easy to tell it's cased.  On this goblet it's impossible to see anything that looks like casing.  There is the scar in the foot which 'seem' to show red in the scar, and the stem being so slim and still faceted so it's difficult to see how it could be cased without either having very thick casing or cutting through it.  The bowl and the foot could both have been cased in and out with clear in the middle but it's very fine and I can't see evidence of that on the cut rim, and it's also faceted completely.

m