RAF Pyro-Metol

[David A. Goldfarb]

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!

 

[David A. Goldfarb]

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.

 

[Claire Senft]

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.

 

[jim appleyard]

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

 

[David A. Goldfarb]

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.

 

[David A. Goldfarb]

Here's Chapman's discussion of RAF Pyro-Metol--

http://www.phototechmag.com/previous-articles/nov99-chem/nov99-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.

 

[john_s]

.........
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). "

 

[David A. Goldfarb]

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.

 

[David A. Goldfarb]

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.

 

[David A. Goldfarb]

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.

 

[Rlibersky]

That looks good. Is the grain in the sky chunky? I couldn't see any in the scan. Certainly looks like a developer worth experimenting with.

 

[David A. Goldfarb]

That looks good. Is the grain in the sky chunky? I couldn't see any in the scan. Certainly looks like a developer worth experimenting with.

Looking with a 6x loupe, the grain in the sky seems big, but I'll know more when I make a real print, which would show if there is a grain masking effect. Here's a neg scan at 1000 dpi, full size, which also isn't an indication of how it will really print, but gives some idea.

I don't think I'd use this for 35mm. I'm mainly interested in using it for 4x5", but if the grain is comparable to ABC pyro or better, I'd go as small as 6x7.

Based on what Haist and Chapman write, I suspect this is going to work best with traditional films that stain well like Tri-X, Efke PL100, and J&C Classic 400.

 

[David A. Goldfarb]

I just ran another test, this time with an indoor scene and incident metering just to be sure my spot readings weren't off on the outdoor shot, and to test a more realistic scenario. Tech V, 6x9 back, 150/4.5 Xenar, TX again, this time developing for 4.5 min at 75 deg., again agitating 10 sec. at the beginning and 2 inversions every 30 sec. thereafter, test exposures ranging from EI 1600 to 8000 in 1/3 stop increments, and the negs look really good. Base fog is down to a more reasonable level, grain is better than I expected (so I would probably use this combo for 6x7, but no smaller), and sharpness is pretty good. I'd say any neg on the roll is printable, but eyeballing it, 3200 looks like the best, which is enough for me.

I'll post a scan when the negs are dry.

 

[Gerald Koch]

No info regarding time, temperature, agitation, or EI.

Don't know if this is of any help. I have the notation that the average development time is 6 minutes at 20 deg C. However, I failed to write down where I got the formula.

 

[David A. Goldfarb]

Thanks, Gerald. That's in line with my results for TX, so it's good to get some confirmation.

Here's a scan of the EI 3200 test frame with a detail at 1000 dpi on the right.

Base fog is down another 12% from the second test roll, and it would be better if I were using fresh film (expired 7/2002). These negs also show some more relief than the first batches.

 

[David A. Goldfarb]

I've been testing with TXT (old Tri-X sheet film, of which I still have enough to make it worth testing), and the results are good, but not as dramatic as with TX. I'll probably call it around EI 1000, with a development time in the 4-5 minute range. That's still better than TXT in Acufine, which I rate at 640, but not as dramatic as the results I was getting with TX. I'm guessing that this has to do with TXT's longer toe, but I didn't expect that big a difference. The emulsion relief is really strong with RAF and TXT. I'll post a test shot once I've fine tuned it a bit more.

 

[David A. Goldfarb]

TXT I'm considering EI 1000, 4 min., 75 deg. for normal contrast.

J&C Classic is looking about the same with better controlled highlight density than TXT.

 

[Helen B]

I was reading ‘Modern Control in Photography’ edited by John Erith (1951). William Pightling mentions RAF pyro-metol as an ‘optional stain’ developer for 'known gross underexposures', and gives three solutions. A and B are as already described (with one small difference, noted below) and C is 8 oz of crystalline sodium sulphite in 80 oz water. For staining it is used as equal parts of A and B, and for non-staining it is equal parts of A, B and C.

The small difference is in the volume. The RAF would use British liquid measures. One fluid ounce is 28.41 millilitres (ie about one ounce Avoirdupois of water), not 29.47 as it is with American liquid measure. 80 oz British liquid measure is 2273 ml, not 2366 ml. Robert Chapman appears to have made the same mis-conversion.

Best,
Helen
PS I guess that it's always worth reminding folks that a British pint is 20 British fluid ounces and an American pint is 16 American fluid ounces.

 

[David A. Goldfarb]

Thanks, Helen. That clears up one mystery, though now that I've been testing it with the wrong volumes, I might stick with them for a while.

 

[Gerald Koch]

The difference in volumes is 4% hardly enough to worry about. It would be hard to detect any difference in density in the negatives.

 

[Helen B]

Gerald,

Yes, I wouldn't expect much of a difference either and consistency is more important than absolute accuracy here. I guess that the quantities of developing agent in the original formulae are probably rounded to the nearest twenty grains (about 1.2 g) or so anyway. I didn't mention the error because I thought that the difference was important, and I didn't think that it was worth mentioning that it wasn't important. I mentioned it because there appears to be an understandable and common lack of awareness of the different liquid measures. It may not have the same potential for catastrophe as the difference in, say, gallons or tons, but I thought that it was still worth knowing. However, if you are going to convert a formula and give the result to three or four significant figures you may as well do it correctly or, maybe better, round it to the same precision as the original formula.

Best,
Helen
PS One thing that did interest me was that for non-staining use the developing agents are a little more dilute, A being diluted 1+2 instead of 1+1.

 

[David A. Goldfarb]

PS One thing that did interest me was that for non-staining use the developing agents are a little more dilute, A being diluted 1+2 instead of 1+1.

I'm a little confused. I thought that in your source, the non-staining version was used 1+1+1 (A+B+C). Does it recommend that it then be further diluted, as in 1+1+1+6 (A+B+C+H20)? In Haist, the staining version isn't diluted at all--just straight 1 part A and 1 part B.

I checked Haist (which was my source), by the way, and indeed, his source is Erith, and I suspect Chapman's source is Haist, unless he also got it from Erith and just made the same error.

 

[Helen B]

"A being diluted 1+2 instead of 1+1"

Sorry for the confusion - I was just simplifying 1A+1B+1C as 1+2 and 1A + 1B as 1+1 to emphasise the comparative dilution of the developing agents in A.

Best,
Helen

 

[Gerald Koch]

Helen,

My post was not intended as any sort of a criticism but rather to make the point that photography is a forgiving medium.

I do appreciate the information about the difference in fluid ounce measurements and have corrected my copy of the formula.

Jerry

 

[David A. Goldfarb]

"A being diluted 1+2 instead of 1+1"

Sorry for the confusion - I was just simplifying 1A+1B+1C as 1+2 and 1A + 1B as 1+1 to emphasise the comparative dilution of the developing agents in A.

Thanks. That makes more sense now.