Only Pyro? Does staining=Pyro?

Discussion in 'B&W: Film, Paper, Chemistry' started by laz, Oct 31, 2005.

  1. laz

    laz Member

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    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
     
  2. Ole

    Ole Moderator Staff Member Moderator

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    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.
     
  3. laz

    laz Member

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    Pyrocat-HD is not a "Pyro"?
     
  4. jnanian

    jnanian Advertiser Advertiser

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    hey bob

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

    noseoil Member

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    What about coffee? It stains teeth as well. Is coffee really a "pyro" as well, because the beans are roasted? tim
     
  6. sanking

    sanking Member

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    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 a moderator: Oct 31, 2005
  7. srs5694

    srs5694 Member

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    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. PhotoJim

    PhotoJim Member

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    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. Gerald Koch

    Gerald Koch Member

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    Pyrocatechin and pyrocatechol are obsolete names for catechol. It is unfortunate that people still continue to use them as it is confusing.
     
  10. Ole

    Ole Moderator Staff Member Moderator

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    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.
     
  11. sanking

    sanking Member

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    I find pyrocatechin in many contemporary scientific sources, not just in the popular literature, with the synonyms of pyrocatechol, catechol, oxyphenol, and even orthodioxybenzene. I allow that it is confusing that everybody does not use the term catechol, but from my perspective there seems to be as much precedent in the literature, including contemporary sources, for the use of pyrocatechin as for any of the other names by which this chemical is known, including catechol. Perhaps it would be best to always double reference the term, say catechol (pyrocatechin) or pyrocatechin (catechol).

    Sandy
     
  12. sanking

    sanking Member

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    What I meant to write was that there are no commercially available staining developers based on hydroquinone. I am familiar with Pat's Q-P-TEA formula and have tested a few variations of it on my own.

    Sandy
     
    Last edited by a moderator: Oct 31, 2005
  13. Leon

    Leon Member

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    well ... there's DiXactol, Dixactol Ultra, Exactol Lux, Precyscol, Precyscol EF ... etc etc

    there are quite a few increasingly popular catechol based developers out there :smile:
     
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  15. Gerald Koch

    Gerald Koch Member

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    Catechol, being a substituted phenol, ends in "ol" as the chemical naming convention says it should. The three dihydroxy derivatives of benzine are thus catechol (1,2), resorcinol (1,3), and quinol (1,4). I concede it would be a very hard sell to get photographers to use the name quinol rather than hydroquinone.

    My reason for not liking the names pyrocatechol and pyrocatechin is that people confuse this compound with pyrogallol and pyrogallic acid.
     
  16. Alan Johnson

    Alan Johnson Subscriber

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    I did not have much luck with this hydroquinone formula found on the net: 10g hydroquinone,1g ascorbic acid, 0.2g phenidone, TEA to 100ml.(Caution,risk present with hot TEA)

    Using the 1:25 dilution with Fortepan 400 film 9m 70F only a faint brown stain was visible when wet and when dry it was hard to see any stain at all.

    I'm not sure that hydroquinone can ever compare with pyro.
     
  17. PhotoJim

    PhotoJim Member

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    Gerald, I'm with you about name confusion. I am an avid tea drinker. Tea comes from an infusion of the leaves of the tea plant (Camellia sinensis or Camellia assamica), much like coffee comes from the beans of the coffee tree. When people take strawberry leaves and ginseng and make "tea" out of it, it drives me crazy. I have to ask for "real tea" and even then people have no idea what I mean.

    I'm kind of tempted to make a percolated or drip-filtered beverage out of ground something... maybe heat-treated gall nuts? So it will be ... pyrogallol coffee? :smile:
     
  18. Gerald Koch

    Gerald Koch Member

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    The french use the term tisane. Definition: Any tea that is made with herbs other than true tea, is called a tisane. Wish other cultures made the distinction.
     
  19. gainer

    gainer Subscriber

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    I seldom use it that way myself. It seemed to be a little known fact that hydroquinone without sulfite could produce a stained image, so I threw it in. The colors of pyrogallol, catechol and quinol are different. In order to see the true color and density of the stain image, one may bleach out the silver with Farmer's reducer. Sometimes the silver image without the dye is not neutral. This effect is more used on paper than film.

    I don't know the Fortepan films. Even Pyrogallol stains different films differently.

    In any case, the QP-TEA may be used as the basis for a more conventional PQ developer by adding sulfite to the working solution. It works quite well with only sulfite as the activator in the manner of D-23. For a quick and dirty test, add 3 tbs of anhydrous sodium sulfite to a liter of 1+50 QP-TEA.
     
  20. Alan Johnson

    Alan Johnson Subscriber

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    I like to make clear the developer I tried was not QP-TEA but had ascorbic acid in it.

    I did not see any reports about the stain density of QP-TEA yet.
     
  21. Alan Johnson

    Alan Johnson Subscriber

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    Hi Jay,

    The test shots were headshots at EI 200 printed on grade 4 VC.For this developer the brown stain was very faint compared to the color of PMK pyro negs.

    It will be interesting if the results with QP-TEA stain get posted one of these days.

    Alan
     
  22. gainer

    gainer Subscriber

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    I don't find the measurements of stained negatives to be very predictive when comparing developers. The stain images of the different agents are of different color, which has an effect on prints in either graded or VC papers. Photographs of a step wedge developed in the different developers and contact printed on both graded and vc papers give a better comparison of the actual contrast to be expected in each case, IMHO.

    If you want to compare different films with the same developer, and can correlate the results with behavior in different printing conditions, well and good. Even so, a good color densitometer costs a lot more than a strip of printing paper, and gives just about as much information.
     
  23. Steve Hamley

    Steve Hamley Member

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    So does pyrocat come from heating cats?

    Steve
     
  24. jimgalli

    jimgalli Subscriber

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    We've got "Mormon Tea" (ephedrine) growing all over the desert out here. Maybe I'll crush some up and see if it will stain film. Could be the next craze. Worst case, I could chew the stuff for a little buzz while I'm doing all these tests.
     
  25. jim appleyard

    jim appleyard Member

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    Microdol-X will turn negs a bit brown, but it has plenty of sulfite in it. Don't know why.
     
  26. c6h6o3

    c6h6o3 Member

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    Any formula with paraphenylenediamine, such as Germain's developer, will also stain. Germain's contains neither pyrogallol nor pyrocatechin.

    I know from experience that Panthermic 777 stains 400TMax, but we don't know what's in that developer. It could have pyrogallol in it as the stain is very similar to what I get with TMY developed in ABC pyro.