Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,553   Posts: 1,544,952   Online: 793
      
Page 1 of 3 123 LastLast
Results 1 to 10 of 27
  1. #1
    laz
    laz is offline
    laz's Avatar
    Join Date
    Aug 2005
    Location
    Lower Hudson Valley (NY)
    Shooter
    Multi Format
    Posts
    1,118

    Only Pyro? Does staining=Pyro?

    The title of this thread just about does it. Are there no other staining developers than Pyro? Google "staining developer" and you find pyro pyro everywhere. (and BTW Google will ask you "did you mean scanning developer!)

    Bob
    [SIZE=1]I want everything Galli has![/SIZE]
    [SIZE=1]I want to make images like Gandolfi![/SIZE]
    rlazell@optonline.net

  2. #2
    Ole
    Ole is offline
    Ole's Avatar
    Join Date
    Sep 2002
    Location
    Bergen, Norway
    Shooter
    Large Format
    Posts
    9,281
    Blog Entries
    1
    Images
    31
    Pyrocatechin stains too - Pyrocat-HD is well discussed here and elsewhere.

    And Hydrochinon can be used in staining developers too.

    In fact just about every developer can give a stain if only the sulfite level is low enough.
    -- Ole Tjugen, Luddite Elitist
    Norway

  3. #3
    laz
    laz is offline
    laz's Avatar
    Join Date
    Aug 2005
    Location
    Lower Hudson Valley (NY)
    Shooter
    Multi Format
    Posts
    1,118
    Quote Originally Posted by Ole
    Pyrocatechin stains too - Pyrocat-HD.
    Pyrocat-HD is not a "Pyro"?
    [SIZE=1]I want everything Galli has![/SIZE]
    [SIZE=1]I want to make images like Gandolfi![/SIZE]
    rlazell@optonline.net

  4. #4

    Join Date
    Jun 2003
    Location
    local
    Shooter
    Multi Format
    Posts
    16,321
    Blog Entries
    5
    Images
    50
    hey bob

    the coffee-based developers ( caffenol &C ) are staining developers.

  5. #5
    noseoil's Avatar
    Join Date
    Oct 2003
    Location
    Tucson
    Shooter
    Multi Format
    Posts
    2,898
    Images
    17
    What about coffee? It stains teeth as well. Is coffee really a "pyro" as well, because the beans are roasted? tim

  6. #6

    Join Date
    Mar 2003
    Location
    Greenville, SC
    Shooter
    Large Format
    Posts
    4,813
    Images
    5
    Quote Originally Posted by laz
    Pyrocat-HD is not a "Pyro"?
    Most people use the term pyro to refer to developers that use pyrogallol as the primary reducing agent. This use is also historic and traditional as the pyro developers in the past were always based on pyrogallol. Popular developers that are based on pyrogallol, to mention only a few of those available commercially, include PKK, WD2D, Pyro ABC, and Rollo Pyro.

    Pyrocatechin (catechol) and hydroquinone are reducers that also produce stained negatives when used in low sulphite formulas. Pyrocat-HD uses pyrocatechin as its primary reducing agent. There is not, at least to my knowledge, any commercial staining formulas based on hydroquininoe, though a number of persons have posted low-suphite staining formulas.

    Th color of the stain can vary significantly according to choice of reducer, accelerator, water quality and choice of film. Pyrogallol based developers tend to produce a greenish/brown stain, pyrocatechin developers a brownish/black stain, and hydroquinone a brownish/red stain. But this is not set in stone, as considerable variation in the color will be seen depending on the choice of options mentioned above.

    As many have observed, the color of the stain can have both subtle and significant differences on results in printing.

    Sandy
    Last edited by sanking; 10-31-2005 at 12:16 PM. Click to view previous post history.

  7. #7

    Join Date
    May 2005
    Location
    Woonsocket, RI USA
    Shooter
    35mm
    Posts
    2,725
    Quote Originally Posted by sanking
    There is not, at least to my knowledge, any staining formula based on hydroquininoe, though a number of persons have posted low-suphite formulas.
    There's Patrick Gainer's Q-P-TEA, published in the March/April 2004 issue of Photo Techniques (check the box labelled "CAT-P-TEA" and read the text):

    100 ml TEA
    0.2 g phenidone
    10 g hydroquinone

    Note that I've not used Q-P-TEA or any other staining developer; I'm just passing on what I've read.

  8. #8
    PhotoJim's Avatar
    Join Date
    Oct 2005
    Location
    Regina, SK, CA
    Shooter
    Multi Format
    Posts
    2,221
    sanking's post said pretty much everything. We should really call the chemical "pyrogallol" (or "pyrogallic acid") and not pyro, since so many chemicals have the prefix "pyro-". These chemicals are derived from the application of heat. Pyrogallol comes from gallic acid from gall nuts. Apply heat... presto, pyrogallol.

    Pyrocatechin isn't nearly as popular but it is still out there. Sanking's well-known formula for Pyrocat-HD is probably the most common developer using pyrocatechin today, although Kodak HC-110 used pyrocatechin as one of its ingredients many years ago.

    The point I wanted to make is that pyrogallol and pyrocatechin don't have to create stain. If the developer is formulated appropriately, it is possible to have no stain at all. Also, use of an acid stop bath and acid fixer can reduce or eliminate stain.

    Also, the stain is usually considered to be desirable as it can enhance acutance and mask grain. It also has contrast effects on variable contrast paper, something that some photographers love and some hate.

  9. #9

    Join Date
    Dec 2004
    Shooter
    Multi Format
    Posts
    1,670
    Pyrocatechin and pyrocatechol are obsolete names for catechol. It is unfortunate that people still continue to use them as it is confusing.

  10. #10
    Ole
    Ole is offline
    Ole's Avatar
    Join Date
    Sep 2002
    Location
    Bergen, Norway
    Shooter
    Large Format
    Posts
    9,281
    Blog Entries
    1
    Images
    31
    Quote Originally Posted by Gerald Koch
    Pyrocatechin and pyrocatechol are obsolete names for catechol. It is unfortunate that people still continue to use them as it is confusing.
    In my part of the world, you have to search for "Brenzcatechin" to find it in chemical catalogues.

    To be very correct and avoid all confusion, the name is 1,2 dihydroxybenzene. Or 1,2 benzenediol.
    -- Ole Tjugen, Luddite Elitist
    Norway

Page 1 of 3 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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