Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,701   Posts: 1,548,417   Online: 1051
      
Page 1 of 2 12 LastLast
Results 1 to 10 of 12
  1. #1

    Join Date
    May 2005
    Shooter
    4x5 Format
    Posts
    159

    Sulfuric (milky) Fixer

    I always get milky fixer when try to add potasium alum to sodium thiosulfate in F6a Ansel Fixer
    the formula is:
    Sodium thlosulphate (hypo) 240.0 grams
    Sodium sulphite (anhydrous) 15.grams
    Acetic acid 48 ml
    Sodium Metaborate 15 grams
    Potassium alum 15.grams
    Water to make 1000 C.c.
    is that any harm to prints?
    How to get rid the milky

    I know there's opinions about not to use hardener but I still want to use it

    thanks a bunch
    quiet-light.blogspot.com

  2. #2
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,069
    Images
    65
    The formula looks fine. The milkiness is not good though. The suspended particles can cause problems with film images and the surface gloss of prints among other problems such as decreased fixing or hardening power.

    The order you give is good, but how much water do you start with? You should start with about 750 ml at about 100 F, then add the first 2 ingredients. When dissolved, add the acid and then the alum. The metaborate should be added slowly while checking pH. The pH should be at about 4.5, no lower, and no higher than 5.5. It should end at about 3.5 - 4.5.

    Is the acetic acid glacial or 28%? This is important.

    PE

  3. #3

    Join Date
    May 2005
    Shooter
    4x5 Format
    Posts
    159
    water 750 ml at first
    yes Acetic acid 28%

    Thanks PE
    quiet-light.blogspot.com

  4. #4
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,069
    Images
    65
    Make sure that the first 2 ingredients are dissolved before adding acid. The early addition of acid can cause sulfurization of the hypo if the pH falls too fast.

    If the pH is too high, then Aluminum Hydroxide will precipitate.

    Hope things work out for you.

    PE

  5. #5

    Join Date
    May 2005
    Shooter
    4x5 Format
    Posts
    159
    the ingredient always dissolved before adding the next, but I'll try to watch the PH

    thanks PE

    Haryanto
    quiet-light.blogspot.com

  6. #6

    Join Date
    Sep 2002
    Location
    Willamette Valley, Oregon
    Shooter
    Medium Format
    Posts
    3,684
    Quote Originally Posted by haryanto View Post
    I always get milky fixer when try to add potasium alum
    to sodium thiosulfate in F6a Ansel Fixer

    How to get rid the milky
    Milky, likely sulfur. Sulfur dissolves in a solution
    of sulfite to form thiosulfate. I've not run any tests.
    Adding additional sulfite may be a harmless way of
    clearing the fix.

    The ph of any of the ingredients listed can vary;
    eg, the alum may vary from 3 to 3.5. I'd likely
    make up the 750 ml with all the more alkaline
    ingredients, dilute the acid in most of the
    needed remaining water then slowly
    with stirring mix the two.

    Is that the method you've used? Dan

  7. #7

    Join Date
    May 2005
    Shooter
    4x5 Format
    Posts
    159
    Yes Dan, the PH is the accurate way to find the problem, PH more than 4.5 when add Pot Alum will make it milky, I've found my Glacial Acetic acid seems not 99.5% so when I make it up to 28% it's not 28%
    I cant measure the percentage of my Acetic acid,
    I had to add Acetic Acid till to 200ml to reach my fixer PH 4
    quiet-light.blogspot.com

  8. #8

    Join Date
    Sep 2002
    Location
    Willamette Valley, Oregon
    Shooter
    Medium Format
    Posts
    3,684
    Quote Originally Posted by haryanto View Post
    Yes Dan, the PH is the accurate way to find the problem,
    PH more than 4.5 when add Pot Alum will make it milky,

    I've found my Glacial Acetic acid seems not 99.5% so
    when I make it up to 28% it's not 28% I cant measure
    the percentage of my Acetic acid,

    I had to add Acetic Acid till to 200ml to reach
    my fixer PH 4
    First a correction. In effect sulfur will dissolve in
    a sulfite solution. Actually the sulfite is oxidized
    by the sulfur into the thiosulfate.

    So which is it to be ph 4 or ph 4.5? How do you
    measure ph?

    If you've an accurate scale and can measure an
    exact amount of the acid the determination of
    the acid's specific gravity will be easy. From
    that the acids strength can be found. Goes
    for dilutions as well. Dan

  9. #9

    Join Date
    May 2005
    Shooter
    4x5 Format
    Posts
    159
    PH 4 is after all ingredients except the P alum dissolved
    I measured PH with PH indicator paper merck, not quite accurate but I notice that in PH 5 I got milky when add the P alum
    do you mean that to dissolves the sulfur I had to add sulfite more? or should I just adjust my acetic acid?

    thanks a lot Dan

    Haryanto
    quiet-light.blogspot.com

  10. #10

    Join Date
    Sep 2002
    Location
    Willamette Valley, Oregon
    Shooter
    Medium Format
    Posts
    3,684
    Quote Originally Posted by haryanto View Post
    PH 4 is after all ingredients except the P alum dissolved
    Do you mean that to dissolves the sulfur I had to add sulfite
    more? or should I just adjust my acetic acid? Haryanto
    Remember, the Alum's ph may be as low as 3. If you are
    at ph 4 then add alum you'll be below ph 4. Adding more
    sulfite may clear that milky fix you've mixed. Test
    a portion. Add and stir in a little at a time. Dan

Page 1 of 2 12 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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