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Thread: Pyrocat HD Stain & Base Fog

  1. #1

    Pyrocat HD Stain & Base Fog

    Hello,

    Just wanted to seek opinions from fellow photographers who use Pyrocat HD.

    I typically develop 8x10 HP5 in Pyrocat HD (1+1+100) using a Stark SST4 Rotary Processor—I develop with the slowest speed settings.

    My question is for unexposed parts of your negatives, e.g. film edges etc, are they plastic clear or do you find yourselves seeing some stain/base fog on these areas? I do in mine.

    I've seen people develop using Pyrocat HD where the unexposed or dark areas are plastic clear and the negatives look really clean perfect for platinum printing.

    Just wondering if it's normal or if there's a way to clear the negative further.

    A test negative of mine attached.

    Thanks

    Sent from my Pixel 2 XL using Tapatalk

  2. #2

    Join Date
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    Re: Pyrocat HD Stain & Base Fog

    always stained. You can use less part B by 20-30% and reduce the stain but then you have to increase time which in turn will effect density. You can always trim your negative if the margins do not give you the effect you want during printing. or tape/cover them the so that they make white borders.
    Adventure is worthwhile in itself. ... Never interrupt someone doing what you said couldn't be done. -- Amelia Earhart
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  3. #3

    Re: Pyrocat HD Stain & Base Fog

    Thanks so for the example I shared t's normal yeah?

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  4. #4

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    Re: Pyrocat HD Stain & Base Fog

    Yep, that's what mine looks like. If you use the normal dilution ratio, there will always be a bit of general stain like on the unexposed edges of the film.

  5. #5
    jp's Avatar
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    Re: Pyrocat HD Stain & Base Fog

    That looks pretty normal (and potentially underexposed but that's subjective).

    There are some instructions out there suggesting a bath in developer after fixing which increases general stain undesirably. No need for that. Normal rinse, develop, rinse, fix, rinse is good.

  6. #6

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    Re: Pyrocat HD Stain & Base Fog

    Quote Originally Posted by jp View Post
    That looks pretty normal (and potentially underexposed but that's subjective).

    There are some instructions out there suggesting a bath in developer after fixing which increases general stain undesirably. No need for that. Normal rinse, develop, rinse, fix, rinse is good.
    JP, Rinsing the negative in the developer after fixing was mentioned in Hutchings "Book of Pyro," a practice that was later retracted. I never saw Sandy King write anything supporting that practice for Pyrocat.

  7. #7

    Re: Pyrocat HD Stain & Base Fog

    If there's any I read somewhere Sandy King uses a dilution acid stop bath.

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  8. #8

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    Re: Pyrocat HD Stain & Base Fog

    There's always some background stain in my negatives, but the density thereof depends on the film used and development time & dilution. I don't find it objectionable in any case so I never spent much time on figuring out how to minimize it.

  9. #9

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    Re: Pyrocat HD Stain & Base Fog

    See https://www.largeformatphotography.info/forum/showthread.php?11159-Pyrocat-HD-or-other-developer-for-drum-processing&p=85141&viewfull=1#post85141

    "...However, when we develop film with rotary processing at high rotation rates the amount of sulfite is insufficient and general stain can result.. To counter this I recommend one of the following solutions: add 30% more of stock solution A when making up the working solution, or (but not also) add about 0.3 g/L of sodium sulfite to each liter of working solution. Both solutions have the practical effect of bumping the amount of sodium sulfite preservative in the working solution and this will slow down the rate of oxidation."
    - Sandy King

    You can also soak your film, after fixing, in a 1% solution of Sodium Sulfite (1 tsp per liter) for ~10 minutes, depending on the chemical composition of your water. This will help reduce the overall background stain, which like the magenta sensitizing dye used in certain Kodak films, amounts to a general fog which lowers effective film speed.

    Note that Sodium Sulfite is the principal ingredient in Hypo Clear Washing Aid and is harmless if not helpful, depending on the type of fixer you use.

    For additional information, see https://www.pyrocathd.5x4.co.uk/

  10. #10
    Vaughn's Avatar
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    Re: Pyrocat HD Stain & Base Fog

    I noticed the base stain varies with type of film and its age -- old Bergger200 can build up quite the base fog stain! TriX seems to give me the cleanest rebates. but again, depends of the freshness of the film, too. Basically, I think the pyro stains the base fog of the film. Most base fog, more stain. I print through it with no issues.
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

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