Author Topic: Photoweight from Broadfield house Museum  (Read 1812 times)

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Offline waltl

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Photoweight from Broadfield house Museum
« on: April 09, 2011, 06:27:51 PM »
Dear Friends,
I saw these weights at the Broadfield House Museum in Stourbridge,England. Does anyone know how they were made? I've done some research and I can't find a satisfactory answer. I contacted the Broadfield House Museum. They don't know. I am a glass worker and I can figure out several ways they might have been made, but I'd like to know actually how they were made.

Thanks for your help


Offline KevinH

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Re: Photoweight from Broadfield house Museum
« Reply #1 on: April 09, 2011, 11:27:19 PM »
Welcome to the Board.

Good question. Personally I have no idea how a photo (or equivalent print of some form) would successfully be set on an opal ground and then encased, unless the encasement somehow included an internal hollow section.
KevinH


Offline waltl

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Re: Photoweight from Broadfield house Museum
« Reply #2 on: April 10, 2011, 01:07:02 AM »
I have inspected them closely. They are solid and the photo is continuous tone ( more like a photograph then a newspaper photo which has dots)
There seems to be a white sheet of glass about half way up upon which the photograph is printed. The quality is very high. There are American weights from Pittsburgh that are similar.



Offline jamalpa36

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Re: Photoweight from Broadfield house Museum
« Reply #3 on: April 10, 2011, 06:33:47 AM »
Hi

Thinking back over twenty years I believe I was once told it was a photographic process where the image was printed onto the white disk.
The term Silver Halide ??? was mentioned.

Maybe one of our photographic experts could help

I just checked on Google  Silver Halide C1900 and this was quite useful

Roy


Offline alpha

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Re: Photoweight from Broadfield house Museum
« Reply #4 on: April 10, 2011, 12:30:22 PM »
At one time I had a similar curiosity. Knowing the weights were made in the late 1800's to early 1900's, I obtained some early photographic books of the period. The books actualy had sections on developing onto white glass. The chemical formulas were old style and needed to be converted into current chemistry which was beyond me. But I believe it is as simple in concept as applying the equivalent to a black and white photographic emusion (containing the silver halide as pointed out by Roy), which was then photographically exposed with a negative. Some stories have it that natural sunlight was used which would require a very slow reactive emulsion. I am sure that similar results could be obtained in a controlled darkroom. The key is the photo emusion. Obviously current photo paper used in a darkroom has the emulsion pre-applied. I do not know of a source of emulsion that could be applied by oneself.

The white disk is then encased in a paperweight. Apparently the silver halide is not destroyed by the glass encasement temperature.

There are also stories of an emulsion that would leave the surface with varying levels of stickiness when exposed with a negative and that black glass powder was then brushed on which would apply in various densities based on the stickiness of the emulsion. Then it was fired on. Personally I thick this was an "old wives tale" meant to mislead those from finding out how it was actually done.


Offline alexander

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Re: Photoweight from Broadfield house Museum
« Reply #5 on: April 10, 2011, 08:20:24 PM »
Peter Von Brackel describes two procedures to produce a photo weight in his book "Paperweights Historicism - Art Noveau - Art Deco" ISBN 0-7643-1052-6. Page 294.

Warning - abbreviated and paraphrased (the full text is a quarter page).

He mentions the "sticky" procedure, where a light sensitive colloidal solution is applied to a ground and exposed to a photo positive creating a sticky surface onto which a black material can be applied.

Another procedure he mentions is where the positive of a photo negative is applied to a colloid skin and treated with either platinum or iridium chloride.

Photo weights from "Bohemia" were made around the turn of the 20th century, tho differing from the weights mentioned here in that the photos are
often on suplhides which are encased in a glass paperweight. Often siting atop a frit cushion.
Alexander
Norwegian glass collector


Offline waltl

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Re: Photoweight from Broadfield house Museum,thanks
« Reply #6 on: April 11, 2011, 04:28:05 AM »
 Thanks everyone for your interesting and informative replies. I had thought about silver, but  silver generally turns glass yellow at higher temperatures. Silver stain is used in stained glass to produce brilliant transparent yellows. Platinum is however very refractory(resistant to high temperatures) Iridium I have no idea. I have heard about the "sticky" thing, but I can't see how it would produce such smooth continuous tones. Perhaps it would be suitable for some things and not others. Anyway thanks for your help.

Yours truly,
Walt


Offline Lustrousstone

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Re: Photoweight from Broadfield house Museum
« Reply #7 on: April 11, 2011, 06:39:40 AM »
I think you can rule out iridium, just too scarce.


Offline tropdevin

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Re: Photoweight from Broadfield house Museum
« Reply #8 on: April 17, 2011, 04:44:08 PM »
***

I am not sure what material was used to provide the black, but from my experience of mixing and firing pottery glazes it might well have been iron oxide. I think the silver would burn off when the glass was heated.  I don't know how the photographic image was translated into metal powder though - whatever the metal.

Some of these photo weights were made at Thomas Webb's factory in Stourbridge by immigrant Czech workers in the early 20th C - a couple brought two into Broadfield House on a paperweight day a couple of years ago, with images of the woman's (English) grandparents.

Alan
Alan
The comments in this posting reflect the opinion of the author, Alan Thornton, and not that of the owners, administrators or moderators of this board. Comments are copyright Alan Thornton. Please feel free to contact me direct if you do not agree with my comments and do not wish to make your concerns known by posting in this thread.
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Offline waltl

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Re: Photoweight from Broadfield house Museum
« Reply #9 on: November 27, 2011, 11:24:40 PM »
Dear Mr. Thornton.
Thanks for your most informative reply. I know you posted a long time ago, but I just read it today.

 

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