Posted 9 years ago
wagesofzin
(24 items)
I got this at auction last month in a lot of four Austrian vases. It's 10 inches and seriously sparkly, and the pontil area has been ground.. No ID, but really sparkly. 8)
Deep Green Striped Sparkly Vase | ||
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Wowser -- Love it !!
TY, Rose! Al, this was ID'd as Harrach. Another vase in the lot was identified as von Poschinger (I'll post it shortly). I understand that green Aventurine is not all that common... is that your experience?
Yep - as far as I have seen, this decor has many times been referenced as Harrach
The lily pad décor in gold on this example is a décor believed to have been produced by both Poschinger and Josephinenhutte. If memory serves me correctly, one of those two used straight lines, and the other used wavy lines in the décor.
As far as the glass itself goes, this form of green aventurine glass is a decor developed with the use of Chromium as an additive to create the color green. The use of extreme amounts of the element causes the creation of "crystals" in the glass when the glass cools. This is as a result of what is referred to as batch over-saturation.
It is the same production method used to create Aventurine glass using copper salts which was discovered in Italy in the mid 1600's.
Chromaventrine glass, as it is referred to by some, is a type of glass that can be found used in the production of Harrach, Poschinger, Josephinenhutte, Legras, Reidel, Monte Joye, and some other companies also. I am not 100% sure, but I believe Loetz also used a limited amount of this glass in their production.
Chromaventurine glass should not be confused with the more commonly seen green glass using mica to create a similar effect. Mica included glass is more commonly found in Deco Era production, and was quite a bit easier and also less costly to produce than Chromaventurine glass.
That is some fantastisch Information, Welz-devil! I have a "Glass Notes" notepad file on my desktop, and this is going straight into it!
Seems it's the Chromium (III) Oxide crystals which precipitate out of the SiO2 solution (aided by tin and arsenic) which becomes super-saturated during cooling. Very thin rhomboids - plates - form, and, interestingly, almost all of them orient parallel to the glass surface.
Very cool stuff! Way back when, in both Uni and workplace chem labs, we would mix (IIRC) potassium dichromate and sulfuric acid to make "squeek" (short for "squeeky clean") to clean lab glassware with prior to making standardized solutions and so on.
A bit off-topic, but still about trace elements in glass, I mentioned in an email to Gary Baldwin that it's a pity there isn't some non-destructive spectrographic method to characterize the base silicas used to make glass by region; in other words, sand from Yunnan China could be differentiated from Kamenicky Vary sand or Nancy sand or Stourbridge or Wheeling WV by characterizing the trace element composition. If it could be done cheaply, then collectors and dealers would have a new tool to use for identifying repros and fakes.
I am glad you found the info useful.
There is a gentleman in the UK by the name of John Franks that did a series of articles in the 90's about Stourbridge glass. A variety of pieces he discussed have now been shown to be Welz production and not Stourbridge. We have discussed a project at a University there where the testing of broken shards would be done to determine just that. Hopefully it will occur at some future point.
THIS IS ALMOST CERTAINLY FREIHERR von POSCHINGER. THE DECOR IS IDENTICAL TO A VASE THEY CURRENTLY OFFER, ALTHOUGH THE SHAPE HAS LIKELY BEEN RETIRED.