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  1. #1

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    Pyrocat: Versions and Mixing Directions

    Pyrocat – Versions and Mixing Directions

    I am attaching mixing directions for various versions of Pyrocat, including –HD, -M, -P, -MC and -PC. I am indebted to Pat Gainer for his advice and recommendations for mixing the glycol based versions of Pyrocat, including Pyrocat-HD, -MC, and -PC.

    Pyrocat-HD is the original Pyrocat formula and is still the most popular judging by sales and questions I get about it. The other formulas, which include Pyrocat-M and Pyrocat-MC, and Pyrocat-P and Pyrocat-PC are recommended primarily for rotary processing, where they tend to give slightly greater acutance than Pyrocat-HD.

    All of the Pyrocat formulas are acutance developers that give good pictorial rendition when used at dilutions of 1:1:100 to 2:2:100 with normal agitation. When used at higher dilutions with reduced agitation they become high acutance developers with very pronounced adjacency effects. Pyrocat can also be used as a two bath developer. See instructions at end of this message.

    Some of the characteristics of all of the Pyrocat variants are:
    1. Good acutance.
    2. Tight grain pattern with some grain masking from stain.
    3. Lower levels of general stain, even with long development times, than most pyrogallol based developers.
    4. Does not cause uneven staining or streaking when developed in Jobo.
    5. Can be used with dilute solutions and minimal agitation for very pronounced adjacency effects and enhanced apparent sharpness.
    6. Very inexpensive to use.
    7. Stock solutions last a long time. A year or slightly more when mixed in water, and up to several years when Solution A is mixed in glycol.

    All of the Pyrocat versions use the same Solution B, which is a 75% solution of potassium carbonate. It is possible to substitute a 20% solution of sodium carbonate but if you do so the working formula must be mixed at 5X the amount of Solution B. Thus, a dilution of One Part A + One Part B + 100 Parts water when using the 75% potassium carbonate solution would become One Part A + Five Parts B + 100 Parts water.


    A. Pyrocat-HD (For one liter of Stock Solutions A and B)
    Part A
    Distilled Water (50° C) 750 ml
    Sodium Metabisulfite 10 g
    Pyrocatechin 50 g
    Phenidone 2.0 g
    Potassium Bromide 2.0 g
    Distilled Water to make 1000 ml

    Part B
    Distilled Water 750 ml
    Potassium Carbonate 750 g
    Distilled Water to make 1000ml

    Mixing Directions for Stock B.
    1. Start with 700ml of distilled water.
    2. Weigh out 750g of potassium carbonate and add the chemical very slowly to the water, with constant and rapid stirring. If you add the solution too fast, or don’t stir enough, it will be impossible to dissolve all of it in the water. As you add the chemical an exothermic reaction takes place and the solution will warm up appreciably.
    3. Add distilled water to 1000ml.
    Tests show that the Pyrocat-A stock solution is stable in partially full bottles for up to a year. If shelf life of longer than one year is desired I recommend mixing Stock A in glycol. Stock Solution B has indefinite shelf life.
    Mixing one-liter of Pyrocat-HD Stock A solution in propylene glycol.

    1. Weigh out all of the chemicals for Stock A.
    50.0g of pyrocatechin, 10.0g of sodium metabisulfite, 2.0g of Phenidone and 1.0g of potassium bromide.
    2. Pre-heat 750ml of propylene glycol to about 150F in a water bath or hot plate stirrer.
    3. Add the pyrocatechin to the warm glycol and stir until dissolved. Should take no more than about a minute.
    4. Add the phenidone and stir. Should dissolve completely in about a minute.
    5. Add the bromide and sodium metabisulfite to about 50-75ml of hot distilled water at about 120F. Stir until completely dissolved, and then add this solution to the propylene glycol solution.
    6. Top off the solution with glycol to 1000ml.

    Pyrocat-HD Stock Solution A, when mixed in propylene glycol, has a shelf life of several years.

    B. Alternative Pyrocat-HDC mixed in glycol.
    Pyrocat-HDC

    Stock A
    Propylene Glycol at 150F 750ml
    Pyrocatechin 50 g
    Phenidone 2.5g
    Ascorbic Acid 4.0g
    (Mix in the order noted and stir until dissolved)
    Glycol to one liter.

    Pyrocat-HDC gives almost identical results as –HD with most films and development methods.

    C. Pyrocat-P (Solution A mixed in water)
    Stock A
    Distilled Water at 120ºF 750ml
    Sodium Metabisulfite 10.0g
    p-Aminophenol 5.0g
    Pyrocatechin 50g

    D. Pyrocat-PC (Solution A mixed in glycol)
    Stock A
    Propylene Glycol at 150F 750ml
    Pyrocatechin 50g
    p-aminophenol 5.0g
    Ascorbic acid 4.0g
    (Mix in the order noted and stir until dissolved)
    Glycol to one liter.


    E. Pyrocat-M
    Stock A
    Distilled Water at 120º F 750 ml
    Metol 2.5g
    Sodium Metabisulfite 10g
    Pyrocatechin 50g
    Water to 1000ml

    Notes:

    1. Mix the chemicals in the order given and stir until dissolved before adding the next chemical.

    2. The use of the potassium bromide restrainer used in Pyrocat-HD is not needed with Pyrocat-P and Pyrocat-M because of the lower pH threshold of metol and p-aminophenol than phenidone.


    F. Pyrocat-MC

    Stock A
    Propylene Glycol at 150F 750ml
    Pyrocatechin 50 g
    Metol 2.5g
    Ascorbic Acid 4.0g


    Mixing directions. Start with about 8ml of TEA at room temperature and a spoonful of water. Now add 2.5 g of metol and stir to make slurry. This is eventually going to make a liter but you can start in a 1/4-liter cup. After the slurry gets a little more fluid, add 15-20 ml of some warm propylene glycol. Now you can transfer the metol slurry to the 750ml of warm propylene glycol and stir until dissolved. Now add 50 grams of pyrocatechin and stir until dissolved. Add 4.0g of ascorbic acid and stir until dissolved. Add glycol to one liter.

    Alternative mixing directions. Heat the glycol to about 250 F and all of the chemicals will readily go into solution with no water required. Mixed this way the solution will be even longer lived. Add glycol to one liter.


    Pyrocat as two-bath developer. Many two-part developers can be used as two-bath developers. Barry Thornton's Diaxactol was originally marketed as a two bath developer, though apparently not a very good one as it was later re-marketed as a single bath developer.

    Pyrocat-HD can also be used as a two-bath developer with excellent sharpness. For this I recommend a 1:10 dilution of both Parts A and B, with solution temperatures at 75F.

    1. Water bath for three minutes. Not necessary for most films but I recommend the water bath for Fuji Acros, Tmax-100, Delta 100, and most fine grain films of ASA 100 or less.

    2. Six minutes in Part A, with two inversions at the beginning, and two inversions at the 1/4, 1/2 and 3/4 points of development.

    3. Pour our Solution A and pour in Solution B. No rinse between. Initial agitation two or thee inversions, then two or three inversions at the 1/4, 12 and 3/4 points of development.

    4. Pour out B, pour in water and leave for five minutes.

    The purpose of the relatively long time in B and the final water bath is to allow developer exhaustion for maximum adjacency effects.

    When used this way Pyrocat-HD is a high acutance compensating developer.

    Pyrocat-HD negatives with the two-bath method described above have higher acutance than with one bath development and intermittent agitation.

    Both Solution A and Solution B can be re-used several times within a three-four hour period but should be discarded at the end of a development session as they will go bad in about 10-12 hours.
    Last edited by sanking; 07-12-2009 at 05:12 PM. Click to view previous post history.

  2. #11
    Bruce Osgood's Avatar
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    THANK YOU SANDY!

    And Patrick, thank you as well. This is a big undertaking and I really appreciate your work and finally bringing all the posts and updates to one (two, counting Gadgets) page.

    I really appreciate it.

  3. #12

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    [QUOTE=gainer;830811]I think my report to Sandy was a little garbled or something. My experiment used a 100 ml of glycerol (also callsed glycerin) to hold the Metol and ascorbic acid. QUOTE]

    Pat,

    No, the report was not garbled -- I just misread it and did not notice you were mixing first the metol ans ascorbic with glycerine and then adding the glycol. Thanks for the correction.

    Sandy
    Last edited by sanking; 07-19-2009 at 02:26 PM. Click to view previous post history.

  4. #13

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    Thanks Sandy,
    The two-part developer method is something I had not read about HD. I wonder if varriatios in time and/or concentrations would yield any usefull variations in contrast,etc.
    Bill

  5. #14
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    Illustrating Pyrocat MC.

    These photos show why I like Pyrocat MC. They are on 35 mm film. The detail is shown in the spine of a book on the shelf between the easy chair and the snow dog portrait. I used 1:1:50, 8 minutes for the FP4+ and 9 minutes for the Arista EDU 400 Supreme at 73 F. The Arista was slightly overdone.
    Attached Thumbnails Attached Thumbnails ARISTA 400 ULTRA.jpg   ARISTA 400 EDU ULTRA DETAIL.jpg   FP4+ Pyrocat MC.jpg   FP4+ DETAIL.jpg  
    Gadget Gainer

  6. #15
    gainer's Avatar
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    I forgot to mention that these photos were scanned from 8x10 prints of most of the negative. The overviews were digitally reduced. The details were scanned at high resolution from small portions of the photo print about a centimeter wide, which makes them about a millimeter wide on the negative. I used no sulfite anywhere along the processing line.
    Gadget Gainer

  7. #16

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    Quote Originally Posted by wildbillbugman View Post
    Thanks Sandy,
    The two-part developer method is something I had not read about HD. I wonder if varriatios in time and/or concentrations would yield any usefull variations in contrast,etc.
    Bill

    Yes, changing the time and/or concentrations will give useful variations. Here is what I posted in another thread about that.

    1. I would recommend that you simplify matters by not changing the time in either Solution A or Solution B. But if you change the time stick with it as it will simplify the other adjustment you can make.

    2. Contrast is controlled by the amount of reducer that can be absorbed by the emulsion in Solution A. Assuming you stay with 6 minutes and 75F, using a stronger dilution will increase final negative contrast, using a weaker one will reduce final negative contrast. In other words, if 1:20 is the norm, a 1:10 dilution will give you more contrasty negatives, a 1:40 dilution will give negatives with less contrast. I think 1:10 is a good starting point for tank development with intermitten agitation, 1:20 is for rotary agitation.

    3. Effective film speed is controlled by the time in solution B. What happens is that the reducer in the emulsion is quickly used up in the highlight areas, and since it can not be replenished as in normal single bath processing, the negative builds contrast rapdily when it goes into the solution, but in about three minutes all of the reducer is used up so that the build up of density in the highlights stops. However, the negative will continue to build up density in the mid-tones shadows throughout development, which increases effective film speed. So if six minutes is the norm for Solution B, four minutes will give less effective film speed, ten minutes will give more effective film speed.

    Sandy King

  8. #17
    Thomas Bertilsson's Avatar
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    For the divided option, how long is the recommended bath in solution B?

    Very interesting read, Sandy. Thanks for posting.
    "Often moments come looking for us". - Robert Frank

    "Make good art!" - Neil Gaiman

    "...the heart and mind are the true lens of the camera". - Yousuf Karsh

  9. #18

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    Quote Originally Posted by Thomas Bertilsson View Post
    For the divided option, how long is the recommended bath in solution B?

    Very interesting read, Sandy. Thanks for posting.
    Hi Thomas,

    I have been using six minutes in both Solution A and Solution B at 75F with the 1:10 dilution for Fuji Acros, rating the film at EI of 50. Less time in B will reduce film speed slightly, more time will increase it slightly, but I think six minutes should be about right for most films.

    Sandy

  10. #19

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    Sandy,

    Do you recommend the same development scheme for TMX 100 as you do for Acros? (I.e. two bath, six minutes each in A and B, 1:10 dilution at 75F?)

  11. #20

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    Quote Originally Posted by Peter De Smidt View Post
    Sandy,

    Do you recommend the same development scheme for TMX 100 as you do for Acros? (I.e. two bath, six minutes each in A and B, 1:10 dilution at 75F?)
    Peter,

    With normal processing Fuji Acros tends to take a bit longer to reach the same contrast than TMax-100 so I might suggest you develop the Tmax less, say 5+5 at the same temperature and dilution.

    Sandy

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