PyroCat Newbie Questions

Discussion in 'B&W: Film, Paper, Chemistry' started by craigclu, Jun 26, 2005.

  1. craigclu

    craigclu Subscriber

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    I've been trying a variety of developers over the past year or so and it's been very interesting to experiment for me. One that I hadn't gotten around to until just recently was Sandy's PyroCat-HD. I don't keep Potassium Carbonate around for anything else but I finally mixed up a batch with the Sodium Carbonate version. I hadn't realized that the pH was so high on this until I checked tonight (about 11.0). I had noticed some emulsion swelling and this is what got me checking pH levels. Is this normal? Is it more apt to occur when using the sodium carbonate? The first of two rolls was done at 80°F as listed at the Massive Dev Chart and I thought this may have been somewhat the cause but the second roll exhibited some swelling, too (not as much, though).

    I've only tried it with 35mm HP5+ on a couple of test rolls so far and had a bit more fog than I expected at .40. Most of my B&W is done on medium format so some of this will be at better levels on that. I assume there are some long-time users of this in here who can fill me in a bit on these questions. I've attached a curve from shooting at 400 and 200 (blue line) 13 min at 70°.
     

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  2. sanking

    sanking Member

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    The pH of 11.0 sounds about normal to me. I usually get about 10.9 with the 1:1:100 dilution using potassium dichromate so we are getting almost identical results in terms of pH.

    High pH will indeed result in some emulsion swelling so if you see any problems drop the temperature, or alternatively use the 2:2:100 for faster develpment times at a lower temperture. I recommend processing with Pyrocat-HD at 68-72º F.

    Sandy
     
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  3. Jeremy

    Jeremy Member

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    I successfully use pyrocat anywhere from 75-85F which is the ambient water temp here in the house.
     
  4. Jorge

    Jorge Inactive

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    Uh, Zone XIII Goal?.......Did you by any chance mean VIII goal?

    Clearly you have a lot of fog and your exposure as well as your developing times were too high. From the curves you presented I would say you need to rate the film at 800 if you plan to continue using the same developing times and temperature. If I was you I would rate the film at 400 and reduce developing time by 30%. I would go with King's suggestion and use 70º F with about the same time, the high temp might have been the cause for the swelling.
     
  5. Andy Tymon

    Andy Tymon Member

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    So when did potassium dichromate get added to pyrocat, is this a new development?:smile:
     
  6. craigclu

    craigclu Subscriber

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    Jorge... I've used that old spreadsheet for a long time and never noticed the labeling error on the chart. Yes, it is supposed to be Zone VIII. For my equipment/materials, it seems that if I keep my Zone 8 in that ballpark, I'm not struggling to hold highlight details. I should have deleted it before posting as it doesn't really pertain to my questions anyway.

    After totally drying, the second roll (at 70°) had very, very little emulsion disruption.

    I can't see where up-rating the film is going to do anything but lose more shadow detail and my mid to highlights are falling right where I would like them to be. The ideal usable EI for HP5 and my equipment would seem to be 200...? What am I missing here?

    In some frames I took of general outdoor scenes, it seems there is quite a bit of detail in the shadows, the grain is quite fine and I like the stain color for VC (I haven't printed anything yet, though). I got very little difference in blue channel curves even though there is obvious stain color. I'll back off a bit on the time and try some different agitation scenarios and also run some medium format and see if the fog settles down for me.
     
  7. Jorge

    Jorge Inactive

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    Craig, I am only going by the charts you presented. It seems you EI falls in Zone III instead of Zone I. This tells me you can give less exposure and less development and basically end up in the same place with a some what thinner negative that would require less enlarger exposure. The advanatge would be that you would enjoy a "faster" film. You could rate HP5 at 400 instead of 200, and meter your shadows accordingly.

    In the end pay no atention to me, yo need to do what is working for you and it seems to me you like a somewhat denser negative than it is required.
     
  8. noseoil

    noseoil Member

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    Quick question about pyrocat & temperature. Does it become much more active as temps increase? I did a couple of sheets of 8x10 this weekend and my usual 4% per degree (f) seemed to be wrong. Second sheet I backed down development by almost a full stop to get what I wanted. Developer was at 76f as summer is here and tap water is now about 90f. Limited room for tempering water in the fridge, too full of film for more water. tim
     
  9. craigclu

    craigclu Subscriber

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    I finally got at doing a 120 HP5+ to get past the base fog issues I was wrestling with on 35mm. I got nice, even results with the PyroCat and only .14 fb+f. I'm attaching a plot.

    Why am I seeing such high fogging on 35mm? I would expect some extra but I'm really getting some big numbers with so many things lately. I'm starting to be suspect of my KBr batch but that should also show on the 120's, too. It's also showing when I use BZT in things. Maybe I'm just more tuned into it as I've been testing so many different concoctions in the past year. The HP5+ 35mm stock I've been using up is either long-frozen stuff of my own or re-spooled bulk packs from re-sellers. There's a chance I'm getting at least -some- more fogged results from those variables, too.

    Thanks to all for their patience and advice!
     

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  10. sanking

    sanking Member

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    Although I have not done extensive testing of Pyrocat-HD at high temperatures my limited experience with it at 75ºF and higher indicates that it increases in energy with increasing temperatures at about the same rate as other developers. At all temperatures, however, Pyrocat-HD builds contrast very significantly from about the 50% point of normal development until the curve starts to shoulder.

    Sandy
     
  11. noseoil

    noseoil Member

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    Thanks Sandy. I was surprised I had to drop times as much as I did this weekend, but it could be a combination of factors, metering etc. which caused this question to arise. My most recent image was the situation I was having a bit of trouble understanding. tim
     
  12. gainer

    gainer Subscriber

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    Clear a piece of unexposed 35 mm HP5+. You will see a density of about 0.2. This is tha antihalation dye. It is in the base and cannot be removed. It is not in 120 or sheet film base, but in the gelatin on the back of the film and is removed by normal processing. Thus you see a difference in B+F between 35 mm and other formats of HP5+.