Becquerel colours?

[csant]

I have been reading through various dag-related material, historic and contemporary. So I came across “The Daguerreotype: Nineteenth-Century Technology and Modern Science” by M. Susan Barger and William B. White. And there it says:

“Some daguerreotypes are colored, especially those produced using Becquerel development. In Becquerel daguerreotypes the colors are not very robust, but they are there, and they are correctly rendered – that is, red objects appear red, green objects appear green, and so forth.” (page 99, quoting from Google Books)

I don’t think I ever saw a (naturally) coloured dag, and my B’dags are all b/w (or, well, with a blue cast…). Could anybody please shed some light on above statement? I’d be very curious…

[photolytic]

While I wholeheartedly endorse the findings of Barger and White, I have certain  comments on the rendering of the colors on Becquerel Daguerreotypes. It is most important to distinguish between regular B-Dags, silver iodide coated plates developed by continuing exposure to light, and Daguereotype images printed out on silver chloride coated plates, both of which were disclosed by Edmond Becquerel.  The prismatic colors recorded on a silver chloride coated Dag plate by Becquerel are the earliest examples of “permanent” color photography which are still visible after 150 years.

I have seen most of the colors mentioned on unfixed mercury developed daguerreotypes as well. For the most part the colors disappear when the Daguerreotypes are fixed.  One can assume from this that the colors are produce by the refraction of light within the silver halide coating.

Like the standing waves which produce the colors on Lippmann plates, such colors are highly dependent upon the distance between the refracting particles. In the case of Daguerreotype plates, these distances change radically when the silver halide is removed from the plate.

Becquerel was not the first 19th Century scientist to observe what is now sometimes referred to a natural color photography.  In 1840 John Herschel reported that he saw the same sorts of colors, as later reported by Becquerel, when he exposed paper coated with silver chloride to sunlight through a prism. He saw the same colors, though less distinct, with silver bromide. With silver iodide he saw complimentary colors. 

Herein lies the caveat. While unfixed silver iodide coated Dag plates appear to record colors, they are not necessarily true to the original colors of the exposing light.  My attempts to use the colors on silver iodide/bromide daguerreotypes plates to produce anaglyphic stereo images have not been successful, whereas similar attempts using silver chloride coated Heliochrome plates reported by Burder in his 2002-2003 Daguerreain annual article worked, “,just”.

 

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[Bakody]

Thank you for sharing this. I’m really interest for this colour daguerreotype possibilities as well. I’m still just reading and studying about this…
How Burder made those dags? Is he used Cl, Br and I for sensitizing or just like in the writing about helichrome “…They were made by coating silver plates for 3 minutes in 3.0 or 4.5% FeCl3 solutions which also contained 2.2 or 2.6% CuSO4 respectively followed by a 5 second rinse in distilled water. …”? Do you know any other try just with Cl, Br, I sensitizing?

http://daginhun.blogspot.com/
 http://www.facebook.com/DagerrotipiaDaguerreotype

[csant]

Thank you very much indeed! You just provided an awful lot of information – and as a dag-n00b, I have quite something to digest… I know about Herschel’s experiments (I have worked for quite a while with calotypes), but this is the first time I hear about silver chloride coated daguerreotypes – and I just discovered your post from a few years ago about your heliochromes… I’d be curious to know about their dynamic range – mercury dags seem to have, from what I am gathering, a larger dynamic range than Becquerel dags. How do heliochrome ones relate to them?

[csant]

…and following up to my questions (now that I have done some background reading on heliochromes): have you ever done in-camera exposures? How would you relate the required exposure time to, say, Becquerel exposure times?

Bakody, please keep us updated on your experiments, as I will do on mine – I am very interested, too.

[Bakody]

ohoo, I will start more seriously experience with this just later. Now for me it’s more important to figure out how to silver plate at home (see in other topic…)
I have read about Lippmann plates as well in this case. So you think the key is the wavelengths (distance change) and not the way to find other sensitizing?

http://daginhun.blogspot.com/
 http://www.facebook.com/DagerrotipiaDaguerreotype

[photolytic]

In the Heliochrome process the images are printed out by the action of sunlight or other bright light. This takes a lot more energy than most forms of photography. Exposure times are similar to that of other printing out processes, such as salt prints, Albumen prints, or silver gelatin printing out paper prints. As such, the times are several hours long without a lens, similar to Becquerel development times.

To get sufficient color saturation the silver chloride layer must be thick and must contain traces of iron and copper.  In his process, Becquerel used electrolysis of sodium chloride to generate chlorine gas which corroded the silver surface. Niepce de st. Victor and Burder used a ferric chloride/copper sulfate solution. A solution of copper chloride will also work but the colors are not as vibrant. Neither process produced an image that could be fixed. In fact even washing the surface of a heliochrome with distilled water will remove the colors, which presumably are dependent on the presence of iron and copper salts in the silver chloride matrix.

Fixing the heliochrome with thiosulfate leaves behind a permanent positive silver image which looks like a B-Dag.

 

 

[photolytic]

Corrected file name

[photolytic]

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[photolytic]

Lippmann plate of fruitbowl made by Darran Green on 14/07/2002.

Collection of David Burder

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[photolytic]

Lippmann plate of fruitbowl made by Darran Green on 14/07/2002.

Reflected vs transmitted light.

Collection of David Burder

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