Pot Bromide v. Pot Ferri ratio affect on Sepia coloring

Discussion in 'B&W: Film, Paper, Chemistry' started by pstake, Sep 6, 2013.

  1. pstake

    pstake Member

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    Can any of the more chemically inclined folks on here help me understand how varying the ratio of Pot bromide and Pot Ferri will affect the darkness/lightness/coolness/warmness/browness/yellowness of sulfer-based sepia toner?

    For example, will a 1 part pot bromide to 1 part pot ferri ratio yield more yellow or darker brown than say, 1 part pot bromide to 2 parts pot ferri?

    I am intentionally excluding all other variables such as bleach dilution and time, paper type. I know those variables effect color as well but I would like info on just this variable right now.

    That said, I would also be interested to know how the amount of sodium sulfide used in the solution, affects coloring.

    Appreciate any info!

    Cheers,
    Phil
     
  2. Ian Grant

    Ian Grant Subscriber

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    There needs to be excess Bromide to ensure good re-halogenation, this usually meand the same weight of both. If there's insufficient bromide you run the risl of forming unstable silver ferricyanide complexes which may wash out before imersion in the toner itself.

    If you want a warmer tone use Sodium Chloride instead of the Bromide. Or better still use a Thiourea toner for greatest variations in warmth.


    Ian
     
  3. pstake

    pstake Member

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    Thanks, Ian. This is the kind of information I was hoping for.

    I plan to mix my own from bulk chemicals (for economy) ... I'm not using Thiourea because I don't want to keep lye around the house.

    Do you have any insight about the volume solution of sodium sulfide and its affect on tone?

     
  4. Ian Grant

    Ian Grant Subscriber

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    The Sulphide is to completion and you only need 5g/litre in the working solution. If it's too weak it's likely to be patchy and uneven in the toning.

    Ian
     
  5. Gerald C Koch

    Gerald C Koch Member

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    There is also a thiourea toner which uses sodium carbonate instead of sodium hydroxide.

    Thiourea 2.0 g
    Sodium carbonate monohydrate 100 g
    Water to make 1 l

    Use FS.
     
  6. pstake

    pstake Member

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    That's good to know, Jerry. But I already have a pound of Sodium Sulfide from the PF. I do have plenty of washing soda, though so maybe when I run out of the stinky stuff I'll try Thiourea.
     
  7. Rudeofus

    Rudeofus Subscriber

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    The great thing about this recipe is that you can fine tune pH with Bicarbonate and achieve unbelievable control over the tone you get, from dark brown all the way to very light yellow.
     
  8. pstake

    pstake Member

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    This is a very attractive quality! Until Gerald posted that you could use bicarbonate instead of sodium hydroxide, I had never heard of this recipe. Maybe I should order Thiocarbamide after all...

    It does raise the question for me, though, as to why you can't adjust the pH of the sulfur solution using bicarbonate, and control the tone?
     
  9. Rudeofus

    Rudeofus Subscriber

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    Note that Gerald posted a Carbonate based mixture, not a Bicarbonate based one. If you add Bicarbonate to Carbonate, you form a Carbonate/Bicarbonate buffer which lets you reliably achieve buffered pH values between about 9 and 11. This is about the range where Thiourea based sulfur toner goes from dark brown (pH 11+) to very light yellow (~pH 9).

    I have no idea how Sulfide based toner would respond to pH changes, but would strongly advise you against experiments. H2S, which will be released in quantity if you are not sufficienty alkaline, is about as toxic as HCN, and your nose will not smell it if concentration of H2S in the air is above a certain level! If you insist on using Sulfide based toner, please follow well reviewed recipes to the letter unless you have a fully equipped chem lab at your disposal.
     
  10. john_s

    john_s Subscriber

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    This post from 2007 might be of interest:


    I find I have the Defender Varigam Sepia toner formulas stored as a text file and include it here because it is in some ways unique. Thiocarbamide has the advantage over Sodium Sulfide of not emitting Hydrogen Sulfide gas so it does not have the familiar "rotten egg" odor.

    Defender Varigam Toner

    Bleach B-1
    Water 500.0 ml
    Potassium Ferricyanide 22.0 grams
    Potassium Bromide 25.0 grams
    Water to make 1.0 liter


    Bleach B-2
    Water 500.0 ml
    Potassium Ferricyanide 22.0 grams
    Postassium Iodide 10.0 grams
    Water to make 1.0 liter


    Bleach B-3
    Water q 500.0 ml
    Potassium Ferricyanide 22.0 grams
    Sodium Chloride 35.0 grams
    Nitric Acid 15.0 ml
    Water to make 1.0 liter


    After fixing and thorough washing prints are bleached in one of the above bleaches for twice the time necessary to visually convert the silver image. They should then be washed until there is no sign of the yellow stain from the Ferricyanide.
    The print is then re-developed in one of the following toning baths.

    Toner T-1
    Water 500.0 ml
    Thiocarbamide 3.0 grams
    Sodium Hydroxide 6.0 grams
    Water to make 1.0 liter


    Toner T-2
    Water 500.0 ml
    Thiocarbamide 3.0 grams
    Sodium Carbonate 45.0 grams
    Water to make 1.0 liter


    Toner T-3
    Water 500.0 ml
    Thiocarbamide 3.0 grams
    Potassium Carbonate 48.0 grams
    Water to make 1.0 grams


    Bleach Toner
    B-3 T-1 Deep Brown, to purplish
    B-2 T-1 Deep Brown
    B-1 T-3 Yellower Brown
    B-1 T-3 Yellow Brown
    B-3 T-3 Very Yellow Brown, "Sunlight effect"

    T-2 used in place of T-3 gives slightly colder tones.

    ---
    Richard Knoppow
    Los Angeles, CA, USA
     
  11. Ian Grant

    Ian Grant Subscriber

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    In Agfa Rezeptes (books of formulae) they give a number of bleaches and toners which can be used in different combinations similar to the Defender Varigram toner above.

    It's worth remembering that best results are with Bromide papers, you can get weaker colours (Dmax) with warm tone papers but there's plenty of room for very significant variations.

    Ian
     
  12. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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    I've been using the potassium bromide and potassium ferrocyanide toner for a while. My process involves bleaching the print with the toner, washing off the toner and re-exposing the print in sunlight which brings back parts of the print. Don't know how it works or what it's called but it makes for unpredictable but beautiful results. I learned this process from a photographer when I assisted years ago.
     
  13. fran

    fran Member

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    Would you have any print scans? that sounds like a really interesting process and one I wouldn't mind trying out?


    Fran
     
  14. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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    Take a look

    Here's a link of a matted print on Flickr. Different papers have a different effect. Sometimes the highlights are beige and the middle and dark tones are brown.

    http://m.flickr.com/#/photos/mainecoonmaniac/9702941117/
     
  15. fran

    fran Member

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    Ok, many thanks for the image.

    So I how far do you bleach and how long in sunlight?.
     
  16. Mainecoonmaniac

    Mainecoonmaniac Subscriber

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    You'll have to experiment

    You'll have to experiment. I bleach the print by eye. Some details disappear in the bleach then come back during re-exposure. But I expose until the print doesn't change anymore under sunlight. You can't get the same results twice no matter how hard you try. Each print is unique with this toning process.