Color Paper Top Emulson Layer

RedSun · Dec 12, 2012

Most of the color papers are coated with various top emulsion cover. For Fuji, it is blue layer.

What does it do? If I understand it correctly, during the pre-wash, this layer is washed away, and the entire emulsion is ready to accept developer chemicals. So it appears this top layer is mainly for protection?

The reason for my asking is that, when I was doing my test printing last time, some of the test strips came out with the un-exposed paper in fainted blue color. That is the same color of the original Fuji color paper. So the top layer was not completely washed away. When I processed the test strips, I pre-wash with warm water for 30 seconds. Then 50 seconds developer and 60 seconds blix. I skipped the final rinse stage and washed the strips in tap water. I normally wash the final prints with rinse chemical for 2 minutes.

I never had the same problem before. So I do not know what had happened. Paper coating change, or chemical change?

Photo Engineer · Dec 12, 2012

You completely misunderstand the layers in color paper.

The structure is /overcoat/Cyan (red sensitive)/interlayer/Magenta (green sensitive) / interlayer/Yellow (blue sensitive)/RC/paper/RCbacking

The paper has this layer order for image stability and sharpness. It contains dyes to also improve sharpness and these dyes wash out during processing. No layer washes off.

If unexposed paper has a blue color after processing, then it was fogged with a red safelight.

PE

RedSun · Dec 12, 2012

PE, I do not think you understood my question.

It is the top layer (or overcoat) I was asking. For Fuji paper, it is light blue. During the pre-wash, I can see clearly that the rinse water came out to be blue. Over time, developer becomes dark, mainly due to the blue color too.

I do not use any safelight with color printing. I've done color printing many times with the same paper, so I know this paper is good. So when the un-exposed paper turns to light blue, I know it is the top layer of the Fuji paper. It was not washed or rinsed properly. This is the first time happened to me and I do not know just why.

To make this go away, I'll have to extend the pre-wash time, or wash the paper with RA-4 rinse. I skipped the rinse stage just because this is only test strip. So it appears I can't skip the final rinse stage.

Hope I could have made things a lit more clearer.

Photo Engineer · Dec 12, 2012

The bluish color of all color papers is due to a dye in ALL of the layers. It is there to adjust speed and to improve sharpness. This dye gradually builds up in the color developer (if you reuse it) and the developer becomes darker and darker blue. Of course, if you follow the published guidelines, you will know if you are putting too much paper through the developer.

In any case, the blue dye is never retained in the coating, nor can it dye the coating blue. Something else causes that blue color. I mentioned red safelight fog. It can also be caused by contamination of the developer with blix, and by omission of the stop bath after the color developer.

If you have leftover dye in the coating (blue dye that should wash out), then a simple re--wash should remove it, but I suspect that you have some other problem. I mentioned several above here.

The overcoat, as I tried to explain in my OP is just plain gelatin! If it is matte paper, then it also contains a matting agent to make the paper have a rough surface. And the dye is uniformly distributed throughout the coating in both Kodak and Fuji papers.

PE

Athiril · Dec 12, 2012

The Kodak papers we have are a brown/tan colour, Fuji is blue.

RedSun · Dec 12, 2012

The blue top layer of Fuji paper is not part of the Dye. It is washed away in pre-wash. It appears to be protective coating, and indicator of the emulsion side of the paper. It is mentioned somewhere that I can't remember. This is the main reason that I'm asking.

Prof_Pixel · Dec 12, 2012

RedSun said:
The blue top layer of Fuji paper is not part of the Dye. It is washed away in pre-wash. It appears to be protective coating, and indicator of the emulsion side of the paper.

I worked on Ektacolor paper for 5 years (in the '70s) and it was made like PE says. I can't imagine any reason for a 'protective coating' or an 'indicator of the emulsion side of the paper'; especially in a layer that washed away.

There might be some specialized material for aero use (or something) that behaves as you describe.

RedSun · Dec 12, 2012

Well, anyone who uses Fuji paper can pitch in. My RA-4 process is 30 sec pre-wash, 50 developer, 60 blix and 2 min RA-rinse. After my pre-wash, the water comes out blue. If this is final large print, the water comes out really blue. That is even before any chemical is poured in.

The last time, when I processed the test strips, I skipped the final 2 min rinse stage. And the test prints came out with the un-exposed part blue, just the same color as the new paper, just lighter. And the edges where the prints attached to the print drum had darker color (blue). It apparently that the test prints were not washed/rinsed properly. So the original blue coating is still on the paper. The un-exposed paper should came out white, just as I had it many times before....

Prof_Pixel · Dec 12, 2012

I think the distinction may be between 'washed OFF' and 'washed OUT'. As PE has said, the blue appearing dye washes OUT during processing. No gel layer is washed OFF. If your prints weren't properly processed, some of the dye may remain. Did you try additional washing?

RedSun · Dec 12, 2012

We are talking completely different thing. This blue color coating (whatever it is) gets washed away during pre-wash, even before developer is poured in. It has nothing to do with any dye.... Do not need to get in developing or processing.

Prof_Pixel · Dec 12, 2012

... so if you take a piece of the unprocessed paper and put a large drop of water on it - with a little rubbing a layer actually rubs off?

RedSun · Dec 12, 2012

You do not need to rub the water, the water turns blue by itself. Almost anyone who processes Fuji paper should know it....

If I hold a piece of Fuji paper in my wet hand, my fingers turn blue quickly.

Prof_Pixel · Dec 12, 2012

See: http://www.docstoc.com/docs/98263147/FUJICOLOR-CRYSTAL-ARCHIVE-PAPER-SUPREME-_ltNEW

Scroll down to 17. Paper Structure and you will see the paper layers exactly as PE described them.

Prof_Pixel · Dec 12, 2012

RedSun said:
You do not need to rub the water, the water turns blue by itself. Almost anyone who processes Fuji paper should know it....

If I hold a piece of Fuji paper in my wet hand, my fingers turn blue quickly.

That is dye coming OUT of the paper. No layer is being washed OFF.

The layer structure diagram I referenced shows the overcoat remains in place after processing.

wogster · Dec 12, 2012

RedSun said:
The blue top layer of Fuji paper is not part of the Dye. It is washed away in pre-wash. It appears to be protective coating, and indicator of the emulsion side of the paper. It is mentioned somewhere that I can't remember. This is the main reason that I'm asking.

Why would you need a dye layer that indicates which side up, on a material that is intended to be in complete darkness until after it's processed. If it's a protective layer, it makes more sense to have it completely clear, so that it does not affect the colour balance. Now if they are trying to correct some aspect of the colour balance, they could put a colour layer on top, which would wash out in processing.

If you know PE's real name, which escapes me at the moment, a lot of the patents for this stuff have his name on them, so I wouldn't argue with the guy, he knows a lot more about this stuff then you or I do.

Prof_Pixel · Dec 12, 2012

wogster said:
If you know PE's real name, which escapes me at the moment, a lot of the patents for this stuff have his name on them, so I wouldn't argue with the guy, he knows a lot more about this stuff then you or I do.

Mowrey

RedSun · Dec 12, 2012

No one answered me as to why the DYE would come out during pre-wash? It does not make sense. So it is not dye.

Have you guys used any Fuji paper?

Prof_Pixel · Dec 12, 2012

RedSun said:
No one answered me as to why the DYE would come out during pre-wash? It does not make sense. So it is not dye.

It's NOT an imaging dye - it's there for sharpness during exposure (as PE said). It's designed to come OUT (note I do not say OFF) during processing (as PE said). It's not part of the image formation proces.

MattKing · Dec 12, 2012

One or more those "guys" have been using, and doing (or supervising and/or reviewing) scientific comparative tests, of Fuji and other non-Kodak materials for decades, as part of their work for Kodak, and on their own.

They designed this sort of stuff!

Athiril · Dec 13, 2012

RedSun said:
No one answered me as to why the DYE would come out during pre-wash? It does not make sense. So it is not dye.

Have you guys used any Fuji paper?

A dye not being fixed in place against a particular solvent doesn't make it not a dye.

Photo Engineer · Dec 13, 2012

I have actually coated color paper. There is no blue dye layer that is washed away. I assure you! The dye alone is washed away.

PE

anikin · Dec 13, 2012

Funny, I had exactly the same impression as the OP. I even made up a theory about it. I thought it was a color filtration layer that would be used by the paper manufacturer to do precise filtration adjustment after all light sensitive layers are coated to correct for batch-to-batch variations of the emulsion. On Fuji paper it surely looks like a surface coat. Maybe I should cut a thin slice and look at it under the microscope to prove myself wrong

RedSun · Dec 13, 2012

That was what I read regarding the Fuji CA paper. I just do not remember the terminology and the source of it. The blue coating does not do much, if I remember it correctly.

Well, whenever you say anything different, there would be many people trying to TEACH you. That is what I've learnt so far at APUG. I just need to learn how to ignore it....

RPC · Dec 13, 2012

I have a question for our paper experts in this thread.

When one prints a color negative without any filtration in the enlarger the print comes out with a strong orange cast. This is counterintuitive to what what one expect. The paper, reversing the colors, should give a strong blue-green cast to the print due to the orange cast of the negative, but it does not. It is as if the paper is negating the orange of the negative and then some. The enlarger filtration of course, negates the orange in the print to make a color-balanced print.

I have always thought that the dyes that wash out of the paper might have had something to do with this paper color-adjusting act during exposure, but now I am not so sure. Just what is going on?

kevs · Dec 13, 2012

RedSun,

Yes you're seeing dye that's dissolving out of the emulsion. You'll see a similar thing if you presoak certain films (FP4+ 120 for instance) - it can be a shock the first time you experience it! Trust me, PE knows a lot more about photographic materials than you, me and most of us on here. APUG is a great place to ask and learn stuff, but some of us don't tolerate fools gladly...

If your blacks are coming out blue on your prints per your OP, your developer is getting exhausted (iirc) and needs changing or replenishing. It's nowt to do with dyes not being washed away...

Cheers,
kevs

Color Paper Top Emulson Layer

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