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Thread: RAF Pyro-Metol

  1. #1
    David A. Goldfarb's Avatar
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    RAF Pyro-Metol

    Anyone try this high-energy pyro formula? I found it in Haist's _Modern Photographic Processing_ (1:458) a while back and finally gave it a go. The formula was developed by the British Royal Air Force in WWI.

    This is the formula as it appears in Haist (these measurements probably come out to nice round numbers if you convert them to ounces and think of a batch as 5 quarts)--

    Part A--

    Metol 9.1 g
    Potassium metabisulfite 10.4 g
    Pyrogallol 10.4 g
    Potassium bromide 3.9 g
    water to make 2366 ml

    Part B--

    Sodium carbonate (crystals) 255.2 g
    water to make 2366 ml

    Mix 1+1 and develop, one shot.

    No info regarding time, temperature, agitation, or EI. I substituted sodium metabisulfite for potassium metabisulfite using the conversion factor recommended in Anchell's _Film Developing Cookbook_. For testing I made 1 liter of each part, and I mixed A and B right before pouring it into the tank.

    I shot a roll of Tri-X (TX) 120 (6x6) spaced at 1/2 stop intervals from EI 100 to 4800, processed 10 min., 75 deg (a little under room temperature), agitating with 2 inversions every 15 sec., 30 sec. water rinse, 3 min in TF-4, 15 min. wash, 1 min Sistan.

    Looking at the wet negs (I still haven't gotten around to replacing my densitometer) base fog/background stain is high, but so is Dmax, so I can cut back on the developing time by at least 50%. In general, I'm suspicious of anyone claiming more than a one or two stop speed increase, but looking at the negs there is good shadow detail at EI 3200!
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    David A. Goldfarb's Avatar
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    Thanks, Jay. I'd worked out the 1 liter conversions but posted it as published in Haist, and your numbers are the same as mine. If you want to substitute sodium metabisulfite for potassium metabisulfite in the 1 liter formula, use 5.1 g sodium metabisulfite.

    The working solution is undiluted--1 part A plus 1 part B.

    And yes, it is grainy, but I'll see if that improves by cutting down the development time, and possibly diluting. I'm mainly interested in using this for large format, so the grain isn't a big issue.

    I'll post some test shots once I've got something interesting.
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    I have never used it. Dr. Robert Chapmam Phd writing in his column in Photo technques magazine has mentioned 3 or 4 times. I hope it works nicely for you.
    Last edited by Claire Senft; 07-14-2005 at 02:40 PM. Click to view previous post history.
    Claire (Ms Anne Thrope is in the darkroom)

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    Another one to try! Sounds like a bit of alright to me.

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    David A. Goldfarb's Avatar
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    Thanks, Claire. I think I've seen one of those references. I should send him an e-mail to see if he has any suggestions.
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    David A. Goldfarb's Avatar
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    Here's Chapman's discussion of RAF Pyro-Metol--

    http://www.phototechmag.com/previous...ov99-chem2.htm

    And I've attached a quick neg scan one of the test shots from this morning (TX, EI 3200, 10 min, 75 deg. F, 2 inversions every 15 sec). There's more detail in the shadows than the scanner could pull out, but this gives a sense of the overall tonality. A neg with a half stop more exposure gives a better scan, but this one should print better.
    Attached Thumbnails Attached Thumbnails RAF,10min,75F,agit15sec,EI3200.jpg  
    flickr--http://www.flickr.com/photos/davidagoldfarb/
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    Quote Originally Posted by jdef
    .........
    Looks like there's the potential for a combination developer/freckle remover in there somewhere. We could call it "Jacko-Cat". The molecular structure of Kojic acid is C6H6O4. Hmmmm. I think I'm going to have to find some of this stuff.
    ..........
    Jay
    And if you added some pyrogallol, it could be an all-purpose skin treatment. The following quote from the US National Toxicology Program Database Information web site:

    "Medically, pyrogallol has been used as a topical antipsoriatic (Budavari, 1996). It was typically applied in an ointment containing 2 to 10% pyrogallol (Stecher, 1968). In Australia, pyrogallol has been used as a topical therapy for chronic plaque psoriasis since the beginning of the century (Pweny, 1925; cited by Willsteed and Regan, 1985), but usage has declined since the 1960s (Willsteed and Regan, 1985). In Europe in the 1970s, pyrogallol was used in conjunction with ultraviolet B for the treatment of resistant psoriasis (Siage, 1976; Meffert, 1970; cited by Willsteed and Regan, 1985). "

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    David A. Goldfarb's Avatar
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    Thanks. I was also curious about the monobath.

    Hydroquinone can be an unstable ingredient in cosmetic formulations. When exposed to air or sunlight it can turn a strange shade of brown.
    I'll have to remember that when I open my Dektol spa.

    I ran another test roll, processing for 5 minutes, agitating with two inversions every 30 seconds this time, and speed still looks to be in the 3200-6400 range and base fog is down to a little more than I'd expect from PMK. Negs are still drying.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
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    David A. Goldfarb's Avatar
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    It does look promising. I would guess it fell out of favor due to grain, the tendency toward smaller formats, better high-speed films, and preference for non-staining developers.

    XR-1 can get a 2-stop boost with fine grain, but low contrast--good for night photography, but not what I really am after.

    I'll keep tweaking and see what I can get.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
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  10. #10
    David A. Goldfarb's Avatar
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    Okay, here's a scan from my second test roll. TX, EI 6400, Y2 filter (3x), 5 min, 75 deg. F, 2 inversions every 30 sec. (Sinar F, 105/2.8 Xenotar, 1/400 sec., f:16, DaYi 617 back masked to 6x9).

    If the scanner is to be believed, base fog was down by 20% from the first roll, and Dmax was more controlled. Less agitation was good for more compensating effect in the shadows. Grain was improved over the first roll, and there might be some grain masking effect going on. I included a detail crop scanned at 1000 dpi and scaled down a bit to fit the APUG size limit to show the shadow detail and give an idea of the grain structure.
    Attached Thumbnails Attached Thumbnails RAF,5min,75F,agit30sec,EI6400.jpg  
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

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