Author Topic: Dating Czech pressed glass  (Read 1164 times)

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Offline Frank

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Dating Czech pressed glass
« on: July 07, 2011, 10:56:20 AM »
While appraising the collection I noticed significant variations in the tints of clear glass. Green, blue and yellow tints plus some black/grey. These are caused by variations in the mixtures of glass and would change over the years for cost or other reasons. With a lot of work it is possible that some guidance to dating can be given. Ideally information from the workers in the factories on the formulae used would be a start. Otherwise it is a case of tabulating the different designs and tints found... eventually some patterns could be found. i.e. certain tints do not appear in pieces designed before date X etc. It would not be an exact science as of course over the years similar tints could appear again.

The only significant, non-methodical, observation I have is that the black/grey tint was 'probably' only found in pre-WW2 designs. The war would of course be a significant factor in changing the sources of materials and thus the need to change formulae.

Working from photographs would not be very effective unless the photographs were taken specifically for the project and a fixed white balance setting and lighting conditions used - with adjustments to the final images taken with reference to the original object to achieve a match.

Here is a good example of variation in green tints. A lidded box. I cannot be certain but it would seem likely that this is a marriage. Yet the fit is perfect. I have yet to find the shape in a catalogue/CGR so cannot be certain that the top and bottom match design wise... although they do appear to be matching.
Frank A.
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Offline KevinH

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Re: Dating Czrch pressed glass
« Reply #1 on: July 07, 2011, 12:55:58 PM »
And it might be possible to assist dating through results of long- and short-wave uv reaction.
KevinH


Offline Frank

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Re: Dating Czrch pressed glass
« Reply #2 on: July 07, 2011, 08:10:30 PM »
Of course Kev, needs a combination of approaches but it could prove a viable if large task.

Product numbers would help too, the Newhall CD dates items by first CGR appearance when lacking any other data. This has the odd effect of putting dates and product codes a little out of synch although might give the information of first production rather than entry into the pattern books and I think it highly unlikely that numbers were not used consecutively.

I guess most of the original pattern books have been lost? Or do they lurk in the archives of remaining companies, collectors hands or museums?

Another fuzz factor may be that some renumbering of pre-war designs took place too. Pamela's catalogue site does have some useful resources for pre-war glass though.
Frank A.
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Offline langhaugh

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Re: Dating Czrch pressed glass
« Reply #3 on: July 07, 2011, 10:31:03 PM »
Frank:

You certainly have an eye for immense projects.  I would imagine that the number of factors would make this an enormous task. I'm not sure at the end of it we'd that much further ahead in any significant sense. For example, for me it's important to know that a particular piece is of low quality and likely to be from a later production. I'd also like to know if it has "Italy" stamped on the bottom. But it's relatively easy to provide that information.

I'd be interested to hear Jindrich's thoughts on this.

David


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Offline Frank

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Re: Dating Czrch pressed glass
« Reply #4 on: July 07, 2011, 11:28:07 PM »
 :thup: You have me sussed. But from what I have seen studying this glass in such depth for the first time is a lot of questions! Having spent 20 years on one factories production I have recognised the value of addressing the minutae as soon as possible - particularly while the people that made the stuff are still around. There is no doubt a huge amount of crud in Czech glass but also a huge amount of seriously remarkable glass - it is debateable where Sklo Union falls in that range as certainly there is a lot more 'high art' in Czech glass, but my pragmatic view is that SU is  in part a parallel to Lalique and deserves a deeper study. There is a huge value in going down this path with SU as it will help later students to understand the subject much better. While it is a big project, the amount of data currently available could be assessed in only a few months. This would provide a good basis for others to start to contribute. Community research efforts can work very well but they do seem to need a strong central driver.
Frank A.
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Offline Anne

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Re: Dating Czech pressed glass
« Reply #5 on: July 08, 2011, 09:29:14 PM »
Frank, your square box above has a similar pattern to the one found on my round green "coaster" type tray, which Jindrich id'd for me as Jablonecké sklo n. p. - sixties - pic here:
http://yobunny.org.uk/gallery1/displayimage.php?pos=-1135 - might be a direction to look in.


Offline Frank

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Re: Dating Czech pressed glass
« Reply #6 on: July 08, 2011, 09:59:25 PM »
The side view will have some surprises but JS sounds possible, Ta. The design on the lid is quite something else.
Frank A.
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Offline Anne

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Re: Dating Czech pressed glass
« Reply #7 on: July 08, 2011, 10:20:00 PM »
Pic please of lid?


Offline astrid

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Re: Dating Czech pressed glass
« Reply #8 on: July 09, 2011, 06:45:55 AM »
Well, I'm certainly not in a position to add anything useful to chemical dating methods, but perhaps I add something that at least gives an indication of age in some of the designs.

I own two Vladislav Urban Moravia vases, triangular shape. Got a blue one first. When I got my second one in, an Amber version, I noticed it was much older than the first one, from the clarity of the detail in the surface structure. In the blue one, the general shape of the Moravia is still present, and the surface structure of the larger protruding bits is exactly the same, but much of the underlying detail is gone, suggesting it was produced a lot later than the Amber one, when the mold had already lost its details.

My deduction of course can be thrown out of the window if it turns out that the loss of detail can also be attributed to a different viscosity of the glass used, in which case the blue glass mixture could have been too thick to settle in the smaller crevices of the mold. I really don't know enough about glass production to say which of the two is the more likely option.

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Offline Lustrousstone

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Re: Dating Czech pressed glass
« Reply #9 on: July 09, 2011, 11:40:30 AM »
It would be a worn mould. The glass is pressed (hard) into place and would always be at the right temperature to flow. I don't think formulation has much to do with it.

 



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