[pure-silver] Re: Yellow colouration in C-41 negatives

  • From: Ken Hart <kwhart1@xxxxxxxxxxxxxxx>
  • To: pure-silver@xxxxxxxxxxxxx
  • Date: Tue, 26 Oct 2021 11:43:24 -0400

(Comments interspersed)

Ken Hart
kwhart1@xxxxxxxxxxxxxxx

On 10/26/21 10:33 AM, Richard Urmonas wrote:

Getting back to some of the comments, and questions:



This is not a scanning effect, the colouration is obvious in the

negatives.  To my eye it looks purple.  It is not a small effect. It is

easy to pick the "good" frames.


Purple/blue on the neg is yellow on the print. Blue is the complement of yellow in color printing, but that blue is more purple than most people recognize. So we're good there.



The effect covers the whole frame but does not extend beyond the frame.

I have not seen any images where the effect covers only part of the

frame, which is what I would expect with a chemical contamination /

degradation.  The effect is also not position in the strip related.




I can't think of any processing method that would affect only the frame, but not the area around the frame. Over agitation can cause the areas around the sprocket holes to receive additional chemical activity, but this effect is not a hard-edge, clearly defined. The processing does not respect the frame borders, so a processing issue might only cover a portion of the frame.

If, for example, the film was processed in a common daylight tank and spool, and not rolled enough or at all, you could have a situation where every Nth frame (the frame at the top and out of the chemicals) was affected. But this would affect the frame AND the edge of the film, and it would not respect the edge of the frame.

I don't think this is filter related.  I don't even think the relative

owned any filters.  There are examples of shots taken not long apart,

similar views on adjacent frames where one has yellowed and the other

has not.

If the 'discolourization' affects only the frame and not the areas around the frame, I can't see any method other than in the camera. The camera exposing the film determines where the frame is on the film. Your statement that there are similar views on adjacent frames where one has the yellow and the other not sounds a lot like experimenting with filters. Perhaps your relative had a secret life, filled with filters that he kept hidden from the family?!


Finally I have a vague memory of having seen some of these images as

photo album prints with neutral colours, so either the mini-lab printer

was able to colour correct, or the effect was smaller when just developed.




Years ago when I owned a mini-lab, it had wide capabilities in filtration. Without much effort, it could print a picture with the color really out-of-whack. The best day of my life was when I hauled that mini-lab to the scrap yard and got fifteen cents a pound for it!

Richard Urmonas


Mr Urmonas has provided great detail on this anomaly. I hope that someone here can come up with a definite answer. I am holding out for it being caused in-camera, but I've been wrong before, and I know what it feels like!

On 2021-10-25T08:57:38.000-07:00, Ken Hart <kwhart1@xxxxxxxxxxxxxxx> wrote:

I want to agree with what someone else (I've lost track of who!)

suggested: what the original poster is seeing is an artifact of the

scanning software. I've seen this myself when scanning color
    negatives.

My flatbed scanner can scan two strips of negatives. It will try
    to pick

the best overall filtration for the entire strips. If one negative is

off exposure by a bit, the filtration will go all wonky. Even if I

select individual frames for scanning, if the exposure is off, it can

have trouble with the color. That's why I'm going to be spending the

next couple days in the darkroom instead of on the computer!



Ken Hart

kwhart1@xxxxxxxxxxxxxxx <mailto:kwhart1@xxxxxxxxxxxxxxx>



On 10/25/21 11:01 AM, `Richard Knoppow wrote:


        The yellow mask is in all color negative materials. Its
        purpose is to
        correct for spurious transmission of certain of the dyes that
        make up
        the image. The built-in mask was invented by a fellow at Kodak
        (you
        know I have trouble with names). In this process the dyes are
        colored
        to begin with and the color is changed in proportion to the
        development. If you examine a color negative through a
        magnifier you
        will see that the mask disappears where certain colors appear,
        thus,
        there is what amounts to a positive mask image along with the
        negative
        printing image. The colored dye mask results in an amber color to
        unexposed parts of the film. I don't think that is what is
        being seen
        here because it is consistent in all parts of the film.

        On 10/25/2021 7:15 AM, BOB KISS (bobkiss) wrote:


            DEAR RICHARD,

            Perhaps I am missing something obvious but do I recall
            correctly that
            color C-41 negatives all have that yellowish/orange cast
            to make
            printing easier, requiring less filtration?Kodak referred
            to it as
            "the mask".I only used C-41 black and white film once
            (because I
            hated the results) so I don't recall if it had the same
            overall cast.

            CHEERS!

            BOB

            -----Original Message-----
            From: pure-silver-bounce@xxxxxxxxxxxxx
            <mailto:pure-silver-bounce@xxxxxxxxxxxxx>
            [pure-silver-bounce@xxxxxxxxxxxxx
            <mailto:pure-silver-bounce@xxxxxxxxxxxxx>] On Behalf Of
            `Richard Knoppow
            Sent: Sunday, October 24, 2021 8:59 PM
            To: pure-silver@xxxxxxxxxxxxx
            <mailto:pure-silver@xxxxxxxxxxxxx>
            Subject: [pure-silver] Re: Yellow colouration in C-41
            negatives

            Is the yellow all over the negative, I mean up to the edges

            rather than just the image area? I am looking for clues.
            Can you

            tell if its on the emulsion side or the support side? The

            question is whether its actually some sort of flare. Old

            Kodachrome slides and prints often had a yellow color from the

            lacquer on them. Two kinds of lacquer, one came off with a
            mild

            alkaline solution like print developer, the other with a
            solvent

            but I don't remember what. I think that is unlikely here
            because

            it would be all over the film.

            Is this color or stain uniform?

            On 10/24/2021 1:01 PM, Richard Urmonas wrote:

                While not strictly silver I was hoping someone could
                shed some


                light on a yellow colouration on C-41 negatives. I
                "inherited"


                the negatives from a family member so I do not know
                the history


                of development and storage, but expect these were
                processed by


                a local 1 hour lab and then stored in a drawer for a
                number of


                years. >From the contents I think these date from the
                1990s.


                The issue I am observing is a yellow colouration
                across the


                whole frame, like a yellow filter was used. This seems
                to have


                happened on random frames and can affect a single
                frame to 3 or


                4 in a row but then have "good" frames. There is even
                a case


                where 2 frames apparently taken a short while apart
                have one


                with the yellow colouration and the other looking
                fine. Note


                that the yellow colour is on the positive image from my


                scanner. The colour shift can be seen on the negative.
                This


                only affects some films, others which have been stored
                together


                with the affected films show no issue. I would have
                suspected


                some colour fading effects, but this does not explain
                the whole


                frame being affected. Can anyone shed some light on
                what might


                be going on?




                Thank you,




                Richard Urmonas







            
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            Richard Knoppow

            dickburk@xxxxxxxxxxxxx <mailto:dickburk@xxxxxxxxxxxxx>

            WB6KBL

            
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