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Author Topic: Glass Types suitable for Pressed Glass  (Read 1098 times)

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Offline Ivo

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Glass Types suitable for Pressed Glass
« on: June 30, 2004, 02:21:22 PM »
I can put your mind at rest about Arnhart - it is German, not Dutch.
I visited Valérysthal several times in recent years and found out why they used glass not semi~ or full crystal. The factory formula was for coloured and clear glass, malleable at a decent temperature and suitable for pressing. It allowed for all the soft opaque colours and great detail in the product. Around 10 years ago when the company failed and was taken over, they were re-established with Portieux as a Cristallerie - meaning their (only) formula now has 29 or 30% lead. This is fine for cut tableware and decanters, but the pressed items suffered greatly. What they turn out of the same moulds nowadays is limited to transparent colours and lacking in detail. I would think that the standard semi-crystal (24%) of Czechoslowakia would not be ideal for pressing either. And wasn't early pressed crystal so flawed by cooling marks that they had to use all-over patterns to camouflage it?
Ivo
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Offline Adam

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Glass Types suitable for Pressed Glass
« Reply #1 on: June 30, 2004, 06:56:38 PM »
Ivo - I know nothing at all about the glassworks you are discussing here, but there is something wrong somewhere.  Lead crystal, 33% is beautiful stuff to press , and to do most other things.  A little slow to set, but that is a problem of production speed not quality.

At Davidsons, although we normally made soda-lime, for one particular order we made a full crystal.  Any defects would be down to poor glassmaking or moulds and not the glass itself.

I am, of course, not talking about colours, but am I missing something else in this discussion?

Regards

Adam


Anonymous

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Glass Types suitable for Pressed Glass
« Reply #2 on: June 30, 2004, 08:01:47 PM »
This is the glassworks famous for hens-on-the-nest and covered dished in soft opaline colours (pink, blue, green, opalescent, coffee etc.) and since the change of formula they make harsh transparent items out of the same moulds with an absolute lack of detail. Could be the moulds have finally worn out, of course....
Ivo


Offline Frank

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Glass Types suitable for Pressed Glass
« Reply #3 on: May 10, 2006, 05:53:11 PM »
According to Hodkin & Cousen, Soda-lime and potash-lime ousted the use of 'expensive' lead crystal and during the 20's Alkali-Barium has proven advantageous over those. Barium glass being more fluid at higher temperatures than lead but sets faster on cooling (Shorter viscosity) thus making it especially suitable for machine pressing.

In other words it allows faster production at a lower cost.

As it is equally as corrosive as lead glass it offers no other benefits.
Frank A.
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Offline Frank

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Glass Types suitable for Pressed Glass
« Reply #4 on: May 10, 2006, 07:00:38 PM »
Another interesting point is that if too much Barium is included in the mix, then the glass will deteriorate.

Does this mean that early deco period pressed glass will turn to dust in time?
Frank A.
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Offline pamela

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Glass Types suitable for Pressed Glass
« Reply #5 on: May 10, 2006, 07:03:47 PM »
Ivo and all,
most interesting thread - thank you! I join Ivo, you see the difference of the material immediately, no need to touch it.

Vallérysthal new
http://www.pressglas-pavillon.de/deckeldosen/02571.html

Vall old
http://www.pressglas-pavillon.de/deckeldosen/02570.html
Pamela
http://www.pressglas-pavillon.de
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