Silver salts in modern enlarging papers

Discussion in 'B&W: Film, Paper, Chemistry' started by timbo10ca, Feb 18, 2009.

  1. timbo10ca

    timbo10ca Member

    Messages:
    590
    Joined:
    Apr 27, 2006
    Location:
    Winnipeg, MB
    Shooter:
    Multi Format
    Very basic question, out of curiosity: What are they? Do the different companies use their own specific concoctions and combinations of bromide, chloride and fluoride for their various paper lines to give different looks and speeds? Or do the other agents present in the emulsions make the major difference and all "warm tone" papers (for example) have the same silver salts/proportions? Or is the paper base itself and sheen the major properties that set different companies apart? All of the above? This is coming from someone who has only ever used paper from 1 company......

    Tim
     
  2. Ian Grant

    Ian Grant Subscriber

    Messages:
    19,461
    Joined:
    Aug 2, 2004
    Location:
    West Midland
    Shooter:
    Multi Format
    No Fluoride and papers fall into 3 categories Bromide, Bromo-chloride/Chloro-bromide and Chloride, the variations depend on the level of Bromide/Chloride.

    Bromide papers are cold toned, Bromo-chloride &Chloro-bromide warm toned the graeter the proportion of Chlodie the warmer they become, and Chloride papers are slow contact speed papers. All the papers can contain a small amount of Iodide, it's often used to help produce different contrast grades.

    Yes formulae do vary from company to company which is why products behave so differently

    Ian
     
  3. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    27,650
    Joined:
    Apr 19, 2005
    Location:
    Rochester, NY
    Shooter:
    Multi Format
    I would add to that Chloro-Iodide and Bromo-Iodide. Modern day emulsions include those as well. Oh well, even old ones were Chloro-Iodide. Lupex was one example from the 40s, but it is used today in some papers to get higher speed and selective spectral sensitivities for VC work.

    PE
     
  4. Ian Grant

    Ian Grant Subscriber

    Messages:
    19,461
    Joined:
    Aug 2, 2004
    Location:
    West Midland
    Shooter:
    Multi Format
    I included the Iodide Ron :D

    The level is significantly lower in papers than films so they've never been called Chloro iodide or Bromo-iodide, but then technically they are, also Chloro.Bromo-Iodide :smile:

    Ian
     
  5. Photo Engineer

    Photo Engineer Subscriber

    Messages:
    27,650
    Joined:
    Apr 19, 2005
    Location:
    Rochester, NY
    Shooter:
    Multi Format
    Ian;

    I know, but I was thinking at the time of the higher iodide emulsions that have expitaxy and are used for high speed modern papers with virtually no blue sensitivity and short green due to iodide + dye. This is often achieved by epitaxy.

    Sorry if it seemed as if I was ignoring your comment, my mind was on this subject (epitaxy and VC) and not the low iodide stuff like Lupex which I added as kind of an afterthought.


    PE
     
  6. OP
    OP
    timbo10ca

    timbo10ca Member

    Messages:
    590
    Joined:
    Apr 27, 2006
    Location:
    Winnipeg, MB
    Shooter:
    Multi Format
    Thanks guys.