Henry William Jackson glass negative from NGM 1989/2 , Is it colorful ?

[Mustafa Umut Sarac]

227437

Hello friends , is this glass negative colorful or because of backlighting ? I found pinks , blues , purples around ! If it is really colorful , why is that ?

[Mark Sampson]

There are several possible reasons. My amateur suggestion; It may be that the emulsion is "mirroring" due to deterioration, from improper processing and/or storage.
This is often seen in prints, and I've seen it in nitrate negatives. But I don't know if glass-plate negatives are affected that way.

[Mustafa Umut Sarac]

There are several possible reasons. My amateur suggestion; It may be that the emulsion is "mirroring" due to deterioration, from improper processing and/or storage.
This is often seen in prints, and I've seen it in nitrate negatives. But I don't know if glass-plate negatives are affected that way.

Mark , What do you mean with mirroring ? Is it a scientific term ? Thanks.

Umut

[Mark Sampson]

Let me consult with my wife; she is a photograph conservator and will help with identification.
In the meantime, let's hope someone already informed will explain.

[profvandegraf]

I see color but I think it is coming from the window they are holding the neg up in front of. Look below to the left of the glass plate, you can clearly see blue sky and buildings reflected on the table top.

[jnantz]

there might be colors because it was taken with a modern digital camera and the world outside and inside where the person is holding the plate has colors reflecting on the glass. I scan black and white materials all the time and the scanner picks up on color in the emulsion too.. so it might be that as well.

[RichardRitter]

A friend of mine worked for the USGS. He started in the sixty's when the USGS was in Washington DC. He found the plates in the basement and they were wrapped in newspaper. It was at the time the USGS was moving out to Reston VA and they were going to trash the plates. He worked with some else and they saved the plates.

So the problem could be from bad storage conditions in the basement or bad processing in the field.

[Tin Can]

I scan BW film & plate with V700 in color

Yes color from computer

Which I like

But not good for OP

Set your DIGI to BW


there might be colors because it was taken with a modern digital camera and the world outside and inside where the person is holding the plate has colors reflecting on the glass. I scan black and white materials all the time and the scanner picks up on color in the emulsion too.. so it might be that as well.

[jnantz]

OP what is the article ? does it say where the negative lives? you might get a definitive answer asking the person who curates HWJ's plates.

[Greg]

dichroic or dichroism: "Glass or crystals showing different colors when viewed from different directions, or having different absorption coefficients for light polarized in different directions" Many years ago used this extensively in Photomicrography of prepared specimen slides.

[Mark Sawyer]

There are several possible reasons. My amateur suggestion; It may be that the emulsion is "mirroring" due to deterioration, from improper processing and/or storage...

Not sure, but I think the mirroring Mark is referring to is silver migration, where the metallic silver migrates to the surface and forms a reflective metallic sheen that may have various colors common to tarnished silver. I don't think it's that though, as that shows up in reflected light, and in this case, the negative is backlit. The reddish brown area in the denser tones may be silver sulfiding, where sulfur from residual fixer (sodium thiosulfate) combines with the image silver to form silver sulfide, which has brownish hues. (That's why we wash our film and prints so thoroughly.) I'll be interested in what Mark's conservator wife thinks.

It could also be that the photo of the negative simply had the color saturation slid up too high.

[Mustafa Umut Sarac]

dichroic or dichroism: "Glass or crystals showing different colors when viewed from different directions, or having different absorption coefficients for light polarized in different directions" Many years ago used this extensively in Photomicrography of prepared specimen slides.

Greg , can we say that silver or silver iodide crystals caused these colors , if they are in really crystal form ?

[Mustafa Umut Sarac]

Not sure, but I think the mirroring Mark is referring to is silver migration, where the metallic silver migrates to the surface and forms a reflective metallic sheen that may have various colors common to tarnished silver. I don't think it's that though, as that shows up in reflected light, and in this case, the negative is backlit. The reddish brown area in the denser tones may be silver sulfiding, where sulfur from residual fixer (sodium thiosulfate) combines with the image silver to form silver sulfide, which has brownish hues. (That's why we wash our film and prints so thoroughly.) I'll be interested in what Mark's conservator wife thinks.

It could also be that the photo of the negative simply had the color saturation slid up too high.

Mark , really interesting , lets wait what she says ?

[John Layton]

If the pinkish color were only present in the shadows then I'd say it was something like crocein scarlet, which would be applied to help retain shadow details in prints. But this does not look so deliberately applied - so either chemical and/or age-related artifacts (such as the sulfiding as described above) or something in the way the backlight affected the photo of the negative.

[Greg]

Greg , can we say that silver or silver iodide crystals caused these colors , if they are in really crystal form ?

I think so. I was photographing specimens from about X2 up to X100 magnification. I think the solidified medium that they were in acted more like glass, but maybe the solidified medium had a microscopic crystal structure to it... Never was able to determine exactly what caused the dichroic colors.

[Mustafa Umut Sarac]

I remembered my research on colorants and different crystal shapes of silver in glass was creating wide range of colors , pyramid shaped crystals were creating one color and the sphere and so on. And colors were appearing with backlighting. I had been read that effect was invented by romans more than 2000 years ago and one of the glass vase was creating enourmous color changes with different temperatures of light. french cathedral near to paris was named as blood of jesus and glass panes was creating blood color with the setting sun and tones were fluiding from top to bottom. I learned this glass was used at middle ages at cathedrals widely. I had been found a picture with these crystals in liquids and backlighted and they were creating attached wetplate colors , extremelly similar. I forgot the name of that technology but I think it is still produced by a factory which served to tiffany .

[Jim Jones]

I believe profvandegraf in post #5 has the most likely answer: blue window lighting and incandescent artificial lighting causing an illusion of color in the glass plate.

[thegreatcornholio]

From my experience you get very cold colored negatives (blue/black) when you either develop very long or intensify/redevelop your negatives. It comes from the reduction of iodides to metallic silver thus a very dense negative (what you would target for POP papers).

It's very interesting to see original negatives, are there more images of Jackson's negatives around?

[John Layton]

William Henry...not Henry William! (c'mon guys...jeeesh!)