Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,499   Posts: 1,543,195   Online: 1113
      
Results 1 to 4 of 4
  1. #1

    Join Date
    Apr 2005
    Location
    San Bernardino, CA
    Shooter
    8x10 Format
    Posts
    734

    chlorinated gelatin

    Hello to all,
    I ran into this website by accident:www.costaricacoffeeart.com
    They sell a chlorinated gelatin that, they claim, can be simply mixed with silver nitrate solution and citric acid to make a working glass negative solution.
    However,after braging that it is 50 to 100 times faster than previous such emulsions, they rate the ISO at 0.5.
    Is it worth looking at as a "starting point"for gelatin emulsion making,as opposed to starting with photo grade gelatin or phthalinated gelatin?
    Regards,
    Bill

  2. #2

    Join Date
    Jun 2004
    Location
    Portland, OR
    Shooter
    4x5 Format
    Posts
    3,268
    Bill, isn't the guy selling gelatin that has some amount of chloride added? Not much value in that it seems?

  3. #3
    Photo Engineer's Avatar
    Join Date
    Apr 2005
    Location
    Rochester, NY
    Shooter
    Multi Format
    Posts
    23,005
    Images
    65
    The ISO of any chloride emulsion is going to be very slow. Silver chloride has most of its sensitivity in the UV region and very little in the visible region. In any event, the size of the crystal (and therefore speed) depends on the making procedure, but in this case if the individual is selling active gelatin, it will speed up the emulsion just by the sulfur present. It will also decrease the stability of the emulsion to keeping unless you add some extra ingredients.

    PE

  4. #4
    ivanp84's Avatar
    Join Date
    May 2008
    Location
    Belgrade, Serbia
    Shooter
    35mm
    Posts
    1
    As biochemist I think that www.costaricacoffeeart.com formula is just simple mixture of gelatin and NaCl. After mixing www.costaricacoffeeart.com gelatin with AgNO3 in darkroom you'll get AgCl colloid in the gel. If you leave on that level you'll never get 100% black, just gray. So you must heat up to 50^C then cool down several times to get proper colloid (in physical chemistry known as Ostwald ripening). The www.costaricacoffeeart.com is very simple formula and I think that I saw in my Serbia a decade ago some high school chemistry projects utilized AgCl + gel + albumin + ...; they printed on unusual materials (rocks, wood, copper, ...)



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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