Topic: Richardson's Vitrified Opaline

[flying free]

trying to link your picture on the main Glass thread - ok that worked so at least there is a picture attached now

[Paul S.]

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. 

[flying free]

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

[cagney]

 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.

[Paul S.]

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.)

[cagney]

 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.

[Paul S.]

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).
 

 

[flying free]

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

[cagney]

 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.

[flying free]

I think that's definitely French, Cagney. 
Best to put on it's own thread though to discuss.

m