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  1. #1
    roy
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    I am about to mix up my Pyrocat chemicals and, with all the talk about the results from minimal agitation, am keen to give this a shot using 120 developing tanks initially. I shall try L/F negs later. The films I have are Efke 25,50 and 100 and I enquire whether any member is able to give me a starter time to get me in the ball park, also with some guidance on the frequency of agitation. Thanks and I apologise if this information is already available !!
    Roy Groombridge.

    Cogito, ergo sum.
    (Descartes)

  2. #2
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    Take a look at Michael & Paula's Azo Forum. Sandy King has done testing of two of these films (25 & 100) and has posted results for BTZS development.

  3. #3

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    Roy, you might also check Unblinking Eye

    http://unblinkingeye.com/Articles/Pyrocat/pyrocat.htm

    There is some additional info there on Pyrocat-HD.
    Mike C

    Rambles

  4. #4

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    Roy,

    In the range of 20ēC thru 25ēC I am currently using a time adjustment factor of 9% per ēC for Pyrocat-HD (1:1:100) tank developed with 5 seconds of gentle agitation per minute (2 gentle toroidal inversions).

    The basis for this 9% factor is the arrhennius reaction rate model for chemical reactions and an estimated activation energy of 0.7 electron volts (based on densitometry evaluations and film mfgr data). Through this 5ēC range, the adjustment factor is approximately constant, to first order.

    When developing Efke roll film in Pyrocat-HD 1:1:100 for the conventional silver enlargement process, I suggest the following starting times to put you in the ballpark:

    1. Efke 100, 10 minutes at 20ēC
    2. Efke 50, 8.75 minutes at 20ēC
    3. Efke 25, 7.50 minutes at 20ēC
    Tom Hoskinson
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    Everything is analog - even digital :D

  5. #5
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    Tom I have a cookie recipe that I think would be perfect for you.
    Non Digital Diva

  6. #6

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    Well... I do bake a mean sour apple pie.
    Tom Hoskinson
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    Everything is analog - even digital :D

  7. #7
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    Chocolate Chip Cookies:

    Ingredients:

    1) 532.35 cm3 gluten
    2) 4.9 cm3 NaHCO3
    3) 4.9 cm3 refined halite
    4) 236.6 cm3 partially hydrogenated tallow triglyceride
    5) 177.45 cm3 crystalline C12H22O11
    6) 177.45 cm3 unrefined C12H22O11
    7) 4.9 cm3 methyl ether of protocatechuic aldehyde
    8) Two calcium carbonate-encapsulated avian albumen-coated protein
    9) 473.2 cm3 theobroma cacao
    10) 236.6 cm3 de-encapsulated legume meats (sieve size #10)

    To a 2-L jacketed round reactor vessel (reactor #1) with an overall
    heat
    transfer coefficient of about 100 Btu/F-ft2-hr, add ingredients one,
    two
    and three with constant agitation. In a second 2-L reactor vessel
    with a
    radial flow impeller operating at 100 rpm, add ingredients four,
    five,
    six, and seven until the mixture is homogenous. To reactor #2, add
    ingredient eight, followed by three equal volumes of the homogenous
    mixture in reactor #1. Additionally, add ingredient nine and ten
    slowly,
    with constant agitation. Care must be taken at this point in the
    reaction
    to control any temperature rise that may be the result of an
    exothermic
    reaction.

    Using a screw extrude attached to a #4 nodulizer, place the mixture
    piece-meal on a 316SS sheet (300 x 600 mm). Heat in a 460K oven for a
    period of time that is in agreement with Frank & Johnston's first
    order
    rate expression (see JACOS, 21, 55), or until golden brown. Once the
    reaction is complete, place the sheet on a 25C heat-transfer table,
    allowing the product to come to equilibrium.

    Now back to your regularly scheduled topic. (sorry for going off topic)

  8. #8

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    Quote Originally Posted by Tom Hoskinson
    Roy,


    When developing Efke roll film in Pyrocat-HD 1:1:100 for the conventional silver enlargement process, I suggest the following starting times to put you in the ballpark:

    1. Efke 100, 10 minutes at 20ēC
    2. Efke 50, 8.75 minutes at 20ēC
    3. Efke 25, 7.50 minutes at 20ēC
    Although I have only tested Efke sheet film these times look about right to me.

    If you want to try minimal agitation increase the times by about 35%. Agitate for the first minute of developmment and for ten seconds every three minutes thereafter, or every two minutes if total development time is less than ten minutes.

    Sandy King

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    Sorry Aggie, but I'm off of lard, peanuts and sodium.
    Tom Hoskinson
    ______________________________

    Everything is analog - even digital :D

  10. #10
    roy
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    Thank you all for your information. I shall let you know how I get on and post some results when I have got my scanner !
    Roy Groombridge.

    Cogito, ergo sum.
    (Descartes)



 

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