Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,927   Posts: 1,556,819   Online: 848
      
Page 3 of 4 FirstFirst 1234 LastLast
Results 21 to 30 of 33
  1. #21

    Join Date
    Aug 2005
    Location
    Los Alamos, NM
    Shooter
    Multi Format
    Posts
    2,062
    Agfa went through a phase where they called for potassium salts in just about everything. Maybe they had a supplier that could give them some business advantage. In any case, I don't know of any noticeable advantage except solubility, and that only sometimes. If anyone has some sound chemical knowledge on the subject, please sound off.

  2. #22
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,330
    Images
    148
    Commercial fixers containing Potassium are still being made today and the formulae aren't necessarily decades old as they've been updated and tweaked to suit modern materials.

    There seems to be a lot of confusion over whether Potassium has a detrimental effects on fixing, if it did then major companies wouldn't use Potassium salts like Potassium Sulphite and Potassium Metabisulphite in fixers. However ther has been a move away from using Potassium Alum as a hardener in fixers to plain Aluminium Sulphate and hardenining fixers tend to use buffered Acetic acid instead of Metabisulpite anyway to maintain a re more stable acidic pH.

    I do mix my own fixers and it's a lot cheaper if you get your Thiosulphate in bulk.

    Ian

  3. #23
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,330
    Images
    148
    Quote Originally Posted by nworth View Post
    Agfa went through a phase where they called for potassium salts in just about everything. Maybe they had a supplier that could give them some business advantage. In any case, I don't know of any noticeable advantage except solubility, and that only sometimes. If anyone has some sound chemical knowledge on the subject, please sound off.
    Agfa were using Potassium Metabisulphite to manufacture Rodinal, with the addition of Hydroxide this splits to form Potassium Sulphite. It was supplied as a concentrated solution.

    Ian

  4. #24
    wildbill's Avatar
    Join Date
    Nov 2004
    Location
    Grand Rapids
    Shooter
    Multi Format
    Posts
    2,454
    Images
    140
    hey!
    anyone care to answer my questions and get the thread back on track? I'm not concerned with agfa.
    www.vinnywalsh.com

    I know what I want but I just don't know how to go about gettin' it.-Hendrix

  5. #25
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,330
    Images
    148
    If you want simple and effective then use 200g Ammonium Thiosulphate and 20g Potassium or Sodium Metabisulphite, alternately use the Agfa 304 formula which is

    Agfa 304 Rapid Fixer

    Sodium Thiosulphate 200g
    Ammonium Chloride 50g
    Potassium Metabisulphite 20g
    Water to 1 litre

    For films and papers.

    (Note this is an Agfa /Orwo formula and not Agfa Ansco/GAF)

    Ian

  6. #26
    wildbill's Avatar
    Join Date
    Nov 2004
    Location
    Grand Rapids
    Shooter
    Multi Format
    Posts
    2,454
    Images
    140
    thank you!
    www.vinnywalsh.com

    I know what I want but I just don't know how to go about gettin' it.-Hendrix

  7. #27
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,330
    Images
    148
    I'm actually using that formula or someting very similar simply because I have plenty of Sodium Thiosulphate and Ammonium Chloride that needs using up, it works very well is equally as good as any commercial fixer.

    Ian

  8. #28

    Join Date
    May 2009
    Shooter
    Medium Format
    Posts
    496
    Quote Originally Posted by Ian Grant View Post
    If you want simple and effective then use 200g Ammonium Thiosulphate and 20g Potassium or Sodium Metabisulphite, alternately use the Agfa 304 formula which is

    Agfa 304 Rapid Fixer

    Sodium Thiosulphate 200g
    Ammonium Chloride 50g
    Potassium Metabisulphite 20g
    Water to 1 litre

    For films and papers.

    (Note this is an Agfa /Orwo formula and not Agfa Ansco/GAF)

    Ian
    Ian,
    Isn't Agfa 304 close to Ole's Quick Fix (OF-1)? Of course Agfa 304 looks like it's easier to brew up and probably works just as well. I had most of the stuff on hand to make Ole's fixer, but had to order some Ammonium Chloride. Should be here by tomorrow. I'm a KISS kind of person as long as the end product does what it's suppose to do and is on the cheap side, since I'm a Dutch kind of person also. JohnW

  9. #29

    Join Date
    Jul 2010
    Location
    Southern USA
    Shooter
    Multi Format
    Posts
    3,952
    The simplest practical fixing bath consists of two chemicals; sodium or ammonium thiosulfate and sodium sulfite. The bath does not have to be acidic if a acid stopbath is used first. However, if a hardening agent such as alum is to be incorporated then the bath must be made acidic before the addition of the alum. The bath may be acidified in several ways. The most common is with acidic acid but sodium bisulfite or potassium metabisulfite can also be used. The acidifying agent must be well diluted and introduced slowly with stirring into a cold thiosulfate solution. It is tricky to make a bath without additional sodium sulfite when using a bisulfite. The solution should contain sufficient sulfite ion before the acid ingredient is added.

    BTW, MSDS forms are not always completley accurate and their interpretation often requires some knowledge of chemistry.

    Ansel Adams mentions the formula for the a two ingredient bath in The Print.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  10. #30

    Join Date
    May 2008
    Location
    Germany
    Shooter
    35mm
    Posts
    302
    My experience with the ammoniumchloride containing AGFA 304 is that it has a tendency to get turbid and separates sulfur more quickly than AGFA 300 since NH4Cl and K2S2O5 give more acidity than K2S2O5 alone.

Page 3 of 4 FirstFirst 1234 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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