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

[Mustafa Umut Sarac]

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.