Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,471   Posts: 1,570,924   Online: 766
      
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 21
  1. #11
    Greg Davis's Avatar
    Join Date
    Feb 2004
    Location
    Crestview Hills, KY
    Shooter
    8x10 Format
    Posts
    1,949
    The sepia tone bleach I have purchased from Kodak contains only Potassium Ferricyanide, so it just part A of Kodak's Farmer Reducer.
    www.gregorytdavis.com

    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

  2. #12
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,392
    Images
    148
    Quote Originally Posted by Greg Davis View Post
    The sepia tone bleach I have purchased from Kodak contains only Potassium Ferricyanide, so it just part A of Kodak's Farmer Reducer.
    Are 110% sure, it not viable.

    Ian

  3. #13
    Greg Davis's Avatar
    Join Date
    Feb 2004
    Location
    Crestview Hills, KY
    Shooter
    8x10 Format
    Posts
    1,949
    What? Are you saying that it isn't viable, or not available? While Kodak doesn't sell it anymore, some stores here still have old stock on the shelves. The bleach portion is packaged separately and is clearly labeled as potassium ferricyanide, as is one of the two packets that make up the Kodak Farmers Reducer that I have on my shelf.
    www.gregorytdavis.com

    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

  4. #14
    cliveh's Avatar
    Join Date
    Oct 2010
    Shooter
    35mm RF
    Posts
    3,559
    Images
    343
    The Ilford manual states (not that you should believe anything you read) –
    Stock bleaching solution
    Potassium ferricyanide 25g
    Potassium bromide 25g
    Water to make 250g
    I have used this and it works fine.

    “The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”

    Francis Bacon

  5. #15
    David Allen's Avatar
    Join Date
    Nov 2008
    Location
    Berlin
    Shooter
    Med. Format RF
    Posts
    492
    The formula that I have for Farmer's Reducer is:

    Stock A:
    Potassium Ferricyanide 19 g
    Water 250 ml

    Stock Solution B:
    Sodium Thiosulfate 240 g
    Water 1 litre

    Mix 30 ml of Solution A together with 120 ml of Solution B and then add water to make 1 litre of working solution.

    A popular variant of the Farmer's Formula purely for use with prints as it is a re-halogenating version of the reducer (which means that, if you over bleach the print you can return it to a developer and build up the density once more).

    Stock A:
    Potassium Ferricyanide 64 g
    Potassium Bromide 30 g
    Water 250 ml

    Stock B:
    Sodium Thiosulfate 120 g
    Water 500 ml

    For controllable use you mix 7.5 ml of Stock A together with 180 ml of Stock B and add 750 ml of Water.

    The formula that I have for a PROPORTIONAL reducer is:

    Stock A
    Potassium Ferricyanide 7.5 g
    Water to make 1 liter

    Stock B:
    Sodium Thiosulfate 200 g
    Water to make 1 liter

    You place your print/negative in solution A for 2 to 5 minutes and then you place it in solution B for 5 minutes followed by a very thorough wash.

    The Adams' formula that I have used most myself (albeit long ago when I had no choice but to use old paper) to clean up veiled/very slightly fogged highlights or to boost the whites of people's eyes in commercial portraits, etc):

    Stock A
    Thiourea 15 g
    Sodium Thiosulphate 700 g
    Water 1 Litre

    Stock B
    Potassium Ferricyanide 75 g
    Water 250 ml

    To make a working stock (does not keep long) you add 5 parts of Solution A to 14 parts Water (Working Bath A) and then combine Working Bath A with an equal quantity of Stock B.


    Many people get happily by with just using the simple Farmer's Formula but I am aware of many friends who have been plagued by intermittent yellow staining / over bleaching / etc who have moved to either the Potassium Bromide variant of the Farmer's Reducer or, more often, to Adams' Thiourea formula.

    Hope that helps.

    Best,

    David
    www.dsallen.de

  6. #16
    Rudeofus's Avatar
    Join Date
    Aug 2009
    Shooter
    Medium Format
    Posts
    1,771
    Images
    10
    Am I correct that if one uses the Bromide+Thiosulfate version of Farmer's reducer, that the print must be fixed afterwards?
    Trying to be the best of whatever I am, even if what I am is no good.

  7. #17
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,392
    Images
    148
    You should re-fix after any reducer. The problem is the ferricyanide breaks down the thiosulphate so you might not completely remove the bleached silver without re-fixing.

    Ian

  8. #18

    Join Date
    Sep 2002
    Location
    Oregon and Austria
    Shooter
    4x5 Format
    Posts
    860
    Quote Originally Posted by Ian Grant View Post
    You should re-fix after any reducer. The problem is the ferricyanide breaks down the thiosulphate so you might not completely remove the bleached silver without re-fixing. Ian
    Yes, anytime the image silver is bleached or rehalogenated, it must be fixed out or it could (will) cause staining later.

    FWIW, I think we need to distinguish between ferricyanide/thiosulfate bleaches (Farmer's, etc.) and the rehalogenating bleaches, which contain bromide.

    What is clouding the issue, I believe, is that you can add thiosulfate to rehalogenating bleaches to speed up the bleaching process (creating a sort of hybrid). However, I use a simple potassium ferricyanide/potassium bromide rehalogenating bleach for both negatives (bleach/redevelop) and prints (both local and overall bleaching) with good results. No thiosulfate at all in the process. I find it more controllable (not to mention reversibly to a certain extent) than Farmer's Reducer.

    For David,

    Bromide in the bleach makes a rehalogenating bleach, as Gerald points out. I works similarly to other ferricyanide bleaches but can be reversed to some extent and some, like myself, find it more controllable.

    Bromide in developers acts as a restrainer and helps prevent fog. It warms image tone a bit in print developers.

    Benzotriazole is an organic anti-foggant, works differently chemically than bromide, but accomplishes much the same thing; a reduction in fog. I cools image tones in prints somewhat.

    Many fine-tune the proportion of bromide and BZT in their print developers to control image tone.

    I'm not sure of the differing roles of bromide and BZT in formulating negative developers. I suspect it is more complex than my current knowledge. I do know that phenidone developers do not react as well to bromide in the formula and, therefore, BZT is usually used as a restrainer if one is needed (the same would apply to print developers also I suppose).

    Best,

    Doremus


    www.DoremusScudder.com
    Last edited by Doremus Scudder; 03-27-2013 at 07:49 AM. Click to view previous post history.

  9. #19
    David Lyga's Avatar
    Join Date
    Nov 2007
    Location
    Philadelphia, PA USA
    Shooter
    35mm
    Posts
    1,306
    Thank you all, especially David Allen, Ian Grant, and Doremus Scudder. You have helped to clarify this, especially with the re-halogenation part.

    If there are further comments, speak. - David Lyga

  10. #20

    Join Date
    Mar 2012
    Shooter
    Medium Format
    Posts
    10
    Quote Originally Posted by Doremus Scudder View Post
    Yes, anytime the image silver is bleached or rehalogenated, it must be fixed out or it could (will) cause staining later.

    FWIW, I think we need to distinguish between ferricyanide/thiosulfate bleaches (Farmer's, etc.) and the rehalogenating bleaches, which contain bromide.

    What is clouding the issue, I believe, is that you can add thiosulfate to rehalogenating bleaches to speed up the bleaching process (creating a sort of hybrid). However, I use a simple potassium ferricyanide/potassium bromide rehalogenating bleach for both negatives (bleach/redevelop) and prints (both local and overall bleaching) with good results. No thiosulfate at all in the process. I find it more controllable (not to mention reversibly to a certain extent) than Farmer's Reducer.

    Best,

    Doremus
    Hi, Doremus

    I want to slightly lighten some parts of my prints on FB warmtone paper and I want a simple reducer formula for that. What's your bromide/ferricyanide formula and how do you use it? Also, if I use only a ferricyanide solution and then wash and fix, will the prints be more prone to strains? (I will selenium tone them subsequently in strong KRST solution for long time).

    Thank you in advance

Page 2 of 3 FirstFirst 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin