Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 73,978   Posts: 1,632,858   Online: 1068
      
Results 1 to 10 of 10

Thread: hca replacement

  1. #1
    RalphLambrecht's Avatar
    Join Date
    Sep 2003
    Location
    Central florida,USA
    Shooter
    Multi Format
    Posts
    7,059
    Images
    1

    hca replacement

    i was wondering, if it makes sense to replace the hypo clrearing agent bath with something closer to sea ater, not eliminating the sodium sulfite (2%)but adding actual sea salt(3.5%)and maybe somemagnesium chloride(0.25%)just a thought, for dis cussion.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  2. #2

    Join Date
    Jul 2010
    Location
    Southern USA
    Shooter
    Multi Format
    Posts
    4,411
    Kodak did extensive tests with various salts and found out that sodiun sulfite was the most effective. IIRC, Agfa tried sodium chloride for a short while then sodium carbonate and finally sodium sulfite.
    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

  3. #3
    Rick A's Avatar
    Join Date
    Mar 2009
    Location
    north central Pa
    Shooter
    Multi Format
    Posts
    6,689
    Images
    35
    Acording to Kodak, sea water for washing prints or film will save about 30% of wash time. They still recommend the use of HCA.
    Rick Allen
    Argentum aevum

  4. #4
    Ian Grant's Avatar
    Join Date
    Aug 2004
    Location
    West Midlands, UK, and Turkey
    Shooter
    Multi Format
    Posts
    16,731
    Images
    148
    Quote Originally Posted by Gerald C Koch View Post
    Kodak did extensive tests with various salts and found out that sodiun sulfite was the most effective. IIRC, Agfa tried sodium chloride for a short while then sodium carbonate and finally sodium sulfite.
    Agfa always recommended Sodium Carbonate right up to their demise.

    Ian

  5. #5

    Join Date
    Oct 2006
    Shooter
    Multi Format
    Posts
    587
    Quote Originally Posted by Ian Grant View Post
    Agfa always recommended Sodium Carbonate right up to their demise.

    Ian
    Hello Ian,
    Is it possible for you to give concentration of carbonate that is suitable for use as clearing agent?

    Jean

  6. #6

    Join Date
    Jul 2010
    Location
    Southern USA
    Shooter
    Multi Format
    Posts
    4,411
    Ian

    You are right I should have checked my notes before mentioning Agfa but I was in a hurry and didn't want to dig them out.

    However from my freshly dug out notes --

    Agfa recommended a 2% solution of anhydrous sodium carbonate. For single and double weight papers, wash the prints for 10 minutes. Then soak the prints for 10 minutes in the working solution with frequent agitation. Finally, wash the prints for an additional 5 minutes. Useful capacity is 100 8x10 prints per gallon of working solution. In any case, the used working solution should be discarded after 24 hours.

    Jerry
    Last edited by Gerald C Koch; 07-27-2012 at 01:29 AM. Click to view previous post history.
    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

  7. #7
    RalphLambrecht's Avatar
    Join Date
    Sep 2003
    Location
    Central florida,USA
    Shooter
    Multi Format
    Posts
    7,059
    Images
    1
    i gather ,the recommendations was identical to sodium sulfite...2%, which is interestinglyvery closely matchingthe global average of sodium chlorideat about 3%.My question again would a combination of different salts work better than hca alone?
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  8. #8
    AndreasT's Avatar
    Join Date
    Sep 2006
    Location
    Berlin
    Shooter
    Multi Format
    Posts
    355
    Somewhere on this sight I once saw a list of different salts (sodium sulfite, Sodium Carbonate etc.) and how effective they are in washing. Where on this site I do not remember.
    It may have been Henk Rolfsa who suggested using 3% Sodium Carbonate and 1% sodium chloride (sea salt). However I am not sure about this.
    Somewhere else I once read that a combination of different salts improve the washing performance of a wash aid.
    Although the sodium chloride must be removed completly because the chloride may damage the photo over time.

  9. #9
    RalphLambrecht's Avatar
    Join Date
    Sep 2003
    Location
    Central florida,USA
    Shooter
    Multi Format
    Posts
    7,059
    Images
    1
    toobad, you can't remembr. i am very inetrestedto find out, but i will conduct my own washing tests regardless!
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  10. #10

    Join Date
    Nov 2002
    Location
    Melbourne, Australia
    Shooter
    Medium Format
    Posts
    1,036
    I have read some posts, probably at rec.photo.darkroom before it went feral, by Richard Knoppow, citing Kodak research describing experiments that eventually showed that sodium sulphite was the best wash aid. As you know in Kodak HCA its pH is adjusted by moderately acidic metabisulphite.

    Agfa used to recommend carbonate but I think the relatively high pH of it can be a disadvantage to the paper emulsion because it softens it. It also might be not at an optimum pH for best rinsing. Isn't there a pH (the pH of Kodak HCA) where the gelatin is in some optimum state for fastest washing?



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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