Paul, thank you for posting the quote /references and your pictures:) both your bowls are just superb.
I don't know if I can agree with his (Lattimore) definition as a current definition. In one sense it is a very 'pure' definition, I think matching the Counts(i.e when opaline glass was first invented and bone ash and/or arsenic were added to the batch as the opacifier, producing a semi translucent glass that was opaline and had an opalescence - see the Count's definition/description and the 1832 recipe)... and so yes I do agree with it in that sense.
However, it does not take into account the developments over time, of 'a glass which has been coloured by adding an opacifier to the batch, such as
bone ash or
tin oxide or
phosphate of lime etc which, when cooled, becomes semi-translucent’ – That is, some of that glass is semi translucent (opaline) but not opalescent depending on what has been added to the batch as an opacifier.
I've based that opinion on the fact I have had a few pieces of French opaline glass which did not display the opalescence, and certainly have opaline glass from other countries that does not either and also the pictures from the Clichy book.
It comes back each time to
- Has opaline glass changed over time in the way it is made?
- Or have definitions changed over time?
- What exactly would be the definition of opaline glass?
It is only my opinion, but from all the pictures and references we have been through, my thoughts are:
a) Opaline glass has changed over time in the way it is made, in that the opacifier has changed. Meaning it no longer always has opalescence, as it did when bone ash/arsenic was used, but is still a 'glass made with an opacifier in the batch, which when cooled gives a semi-translucent effect',
b) The definitions for opaline glass have changed over time to account for this (e.g. Mehlman V the Count)
c) The definition of opaline glass needs to encompass opaline glass which is ‘flat’ i.e. has no opalescence and also that which is opalescent.
But I also have been thinking (and these thoughts I’m sure are going to be controversial and are up for discussion
- Opalescent or opalescence is an effect in or on glass but is not a type of glass.
and that is why I can't find any definitions in books or online for 'Opalescent Glass...'
The reason for the thoughts above are that I have also been musing on the following (again these are just my thoughts and open to correction and discussion
That there are three types of glass created in the batch:
- Transparent (Adjective (of a material or article) Allowing light to pass through so that objects behind can be distinctly seen )
- Translucent (Adjective (of a substance) Allowing light, but not detailed images, to pass through; semi-transparent)
- Opaque (Adjective Not able to be seen through; not transparent)
So for example;
- flint, or amethyst or cranberry glass or any colour transparent glass would fit under ‘Transparent’
- the examples of milchglass or lattimo or hyalith or lithyalin (just a few I could think of) would all fit under ‘Opaque’
- opaline glass would fit under ‘Translucent’
but opalescent glass does not fit under any of the types because it is not a ‘type’ of glass but an ‘effect ‘ in or on glass … so
it can be an effect on or in translucent, or opaque or transparent glass depending on how it is created,
i.e. whether it is an effect created:
- in the batch (the effect seen on some translucent glass i.e. opaline glass (and also girasol which I also think is a type of opaline glass) and possibly also opaque glass made using bone ash. Lalique opalescent glass would come under this I think (**see below).
- as an effect of cooling and reheating e.g. on the edges of transparent glass in the case of Pearline,
-on glass blown into a raised patterned mould in two layers, and where the outer layer is translucent (opaline) made using bone ash and /or arsenic as an opacifier and so on reheating the outer layer on the raised pattern becomes opalescent.
** Source - ' Rene Lalique & Cie The Complete Illustrated Catalogue for 1932'
In the English translated introduction in this catalogue Gabriel Mourey says'...Whether he chooses for his material colorless, polished or frosted glass, opaline glass or colored glass (black,smoky,jade-green, sapphire blue, red, rainbow; whether he uses the technique of molded or cut glass, or combines these two processes, his imagination knows no limits....'
In the original French paragraph he calls it '...le verre opalin'
- there is no mention of opalescent or opalescence as far as I can find.
These are my thoughts
I would welcome contributions and discussions and to whether or not they make sense
With regards the definitions of opaline glass over time -
I think it is important to find early descriptions written when the glass was first developed, as well as descriptions over time, and the ‘more recent’ descriptions looking back, if you see what I mean, as there are discrepancies between what is described as opaline glass now and what was then, from the sources we've referenced so far.
(And I have not been able to find an early reference to something called 'opalescent glass' in those sources? or have I misremembered? Have you come across anything called 'Opalescent glass' or is it all 'Opaline glass that has opalescence' type descriptions? )
I have been searching early- mid 19th century French books and I have found another description written in France in 1853
It’s quite a small piece, interesting, but difficult to 'interpret' what is really meant by it:
Source: There were a number of editions of this book called
'Manuel complet du verrier et du fabricant de glaces '
by M. Julia de Fontenelle and Francois Malpeyre
In the one of 1829 there is no mention of opaline glass or opalescent glass except under mention of sapphire blue glass where they discuss in one part about the blue having an opalescence ( I think)
However in the 1853 edition there is a description headed:
'Verre opalin ou opalescent' (Opaline or Opalescent glass)
It reads as follows (translated by Google translate - original below without 'accents' unfortunately)This is a milk glass resembling the alabaster or opal that has prepared the way ordinary, with the addition of
a greater or lesser quantity of calcined bones.
It goes on to talk I think about making opaline uranium glass (I think talking about that uranium opaline glass can be created instead of opalescent opaline glass ...but don't quote me on that as I found it quite hard to understand exactly what was being described)
‘ Glass can be manufactured in a top quality with a greenish reflection with the following mixture
yellow oxide of uranium
It is claimed that the colored glass mixture with previous change of color under the influence of sunlight and we can prepare a glass of a color more beautiful and withstood the action of the sun by substituting nickel oxide in forge slag
So it seems to me that, written in 1853 in France, this appears to be describing a type of glass and calling it ‘either opaline or opalescent’. It is the first time I’ve come across a description naming ‘opalescent’.
Still investigating, but I think at the moment I would still call your both your bowls and the pieces from the Bonhams link, opaline glass
French original from book above (missing accents, my lack of keyboard knowledge sorry)
'C'est une verre laiteux ressemblant a l'albatre ou a l'opale qu'on prepare a la maniere ordinaire, avec addition d
'une quantite plus ou moins forte d'os calcines. On peut fabriques le verre d'une qualite superieure avec un reflet verdatre avec le melange suivant
oxyde jaune d'urane
scories de forge
On pretend que le verre colore avec le melange precedent change d couleur sous de influence des rayons solaires et qu'on peut prepare une verre d'une couleur plus belle encore et que resiste a la action du soleil en substituant l'oxyde de Nickel au scories de forge'
As I said, all up for discussion
and these are just my thoughts