Getting the red out, again.

Discussion in 'B&W: Film, Paper, Chemistry' started by Maine-iac, Feb 5, 2005.

  1. Maine-iac

    Maine-iac Member

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    There was a thread or two some time ago about getting the purple dye out of T-grain films. At the time, I think I remember saying something to the effect that I had noticed this intermittently, and that sometimes it came out and sometimes it didn't.

    Anyway, just yesterday, I developed 8 sheets of film in my trays. All were Delta 400, loaded at the same time from the same sub-packet (the sub-packets are the 25 sheet individual packets in a 100-sheet box of film). All were exposed on the same outing, all were developed in the same developer at the same time for the same duration, N+1. Seven of the sheets came out with no purple; one of them came out with a lot of purple still on the film. Go figure.

    I theorized (logically, I think) that if I re-fixed and ran it through the washing aid again, perhaps it would come out. I did, and after a five minute wash, some of the purple came out, but not all.

    I'm about to conclude that Ilford's coating processes were not consistent. I can't think of anything I did that could account for one sheet out of eight coming out different.

    Larry
     
  2. SteveGangi

    SteveGangi Member

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    If I remember, the purple is the anti-halation layer stuff whatsis thingy. A second fixing and more washing should get rid of it. That was the general way to deal with TMax, which is Kodak's T grain film.
     
  3. rjr

    rjr Member

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    Steve,

    it´s more like a "sensitisation dye" thingy, making the film panchromatic. ;-)

    Refixing is just curing the symptoms with a strong poison, you gain nothing by facing the film with the thiosulphates for a longer period than double or tripple the clearing time.

    The stain should be soluble with a alkaline solution like a bath of sodium sulfite or sodium carbonate, followed by a normal wash - that helped with the TMZp3200 I processed last year.

    With Efke R50 sometimes this is a futile approach - only hanging the pergamine sleeves with the cut negatives on the window for 2 or 4 hours helps (ie bleaching with Sun light).
     
  4. Maine-iac

    Maine-iac Member

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    I did fix a second time, and I also used Perma-wash a second time, and at an even stronger dilution than recommended, followed by an even longer second wash. While some of the remaining purple did come out, not all of it did. Why this one sheet out of eight that were all from the same film packet and exposed at the same time?
     
  5. matt miller

    matt miller Subscriber

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    I use sodium carbonate in the pre-soak to remove the dye for easier DBI. About 20g in 1 liter water is what I use. It works well.
     
  6. dr bob

    dr bob Member

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    Roman is correct. The pinkish – purplish cast in most negatives is caused by the sensitizing dyes not being completely removed through “normal” processing. The anti-halation coating is on the non-emulsion side of the film and is usually completely decolorized in the developer.

    There seems to be no detrimental effects by leaving the color as is. However if complete removal is desired, just soaking the negatives in a series of water baths for a few minutes each can do it. HCA baths will also help.