Pyro in the May/June "Photo Techniques"

[Kevin M Bourque]

The May/June “Photo Techniques” contains an article by Howard Bond in which he compares Pyro to D76. He shot several identical high-contrast scenes (snow on mountains) on 5x7 T-Max 100 and compared the resulting prints at 4.5x enlargement.

According to him, the prints are identical in terms of sharpness, and nearly the same in tonal range. He is convinced that a little extra work would make them identical. He ends that article by asking to see similar pairs of prints that show a substantial difference between pyro and any other developer.

He also raises some questions about the possible toxic effects of pyro.

Clearly, he sees no reason to use the stuff, and is asking for a careful, experienced printer to show him why Pyro is special.

[Ken Lee]

Howard Bond seems to have drawn an unfortunate and misleading conclusion. Out of all possible films with which to test Pyro, he chose the one most widely rejected for use with that kind of developer.

Had he chosen almost any other film, his comparison would have probably reached the same conclusion reached by several respected researchers, already in print and freely available on the web.

[Richard K.]

T-Max 100 has got to be the worst choice for gleaning Pyro effects since they are so minimal with this film. Not that Mr. Bond is necessarily wrong, but just about any other film (including T-Max 400) would have been a better choice and provided enhanced basis for comparison.

[Jorge Gasteazoro]

He is convinced that a little extra work would make them identical.

This is exactly the point, why work harder when you can use a developer that allows you not to. There is no doubt n my mind that you can make them work the same, but then the idea is to get a better neg with less work, no?

[Jorge Gasteazoro]

You know, now that I think about it, there might be a reason why pyro developers are better. Since the light tones in the negative have less silver and part of the density comes from the stain, it might be that given a certain developing time to build the high tones might also build the middle tones a little bit more, thus giving better separation for the middle tones as well.

This is just speculation and I will try some tests to see if this is true. It might not be, but sounds reasonable.

[bob moulton]

Question for those who read the article: How do advocates of the various forms of pyro respond to the charges about toxicity? i agree that bond could have chosen a different film for his testing. But so far no one has addressed his concerns about the dangers of the chemistry. How come? Are Bond and the sources on which he relied wrong?

[David A. Goldfarb]

I also have to agree that the film choice is just wrong, if he was looking to produce an interesting result. Pyro is great with Tri-X and Efke PL100 in my experience, but when I shoot TMX, I prefer D-76 (1+1).

[Jorge Gasteazoro]

Question for those who read the article: How do advocates of the various forms of pyro respond to the charges about toxicity? i agree that bond could have chosen a different film for his testing. But so far no one has addressed his concerns about the dangers of the chemistry. How come? Are Bond and the sources on which he relied wrong?



They are not wrong, they are simply exaggerated, let me give you an example. Hydroquinone, a developer that nobody fears, most people stick their hands in it and nobody has ever said is toxic has the chemical formula of p-dihydroxybenzene. Pyrogallol OTOH is hailed as the poison bane and people warn your arm will fall off if you stick your hand in the developer, yet the chemical formula is 1,2,3 trihydroxybenzene, furthermore catechol is o-dihydroxybenzene. It is not clear if the position of the hydroxy groups aids or prevents absorption through the skin, but I would doubt the difference would be so great as to make any difference in the toxicity.



The problem that arises from using pyro or catechol is that most of the time it has to be mixed from raw ingredients, as such the possibility of inhaling the chemical is greater than using a mixed developer. I am not aware of any studies but given the chemical formulas and properties I would say if you inhale hydroquinone you would be in as much danger of intoxication as if you inhale pyrogallol or catechol, yet nobody says anything about hydroquinone.



This was also magnified by that woman who published a book on darkroom toxicity which was full of errors and exaggerations. People without a chemical background as well as health and safety read this book and continued to propagate the myth that pyrogallol is more toxic than the usual photographic chemicals. This is wrong, let me put it this way, no benzene derivative is good for you, most photo developers are benzene derivatives, so you certainly do not want to use them to make soup, but with normal care and sound lab practices, pyrogallol and catechol are not any more toxic than your run of the mill paper or film developer.

[Gem Singer]

Hi Jorge,

The literature seems to be filled with cautionary statements regarding the rate of absorption through the skin of pyro compounds, as compared to other combinations of developing agents. They say that pyro absorbs very quickly. Any truth to that? They always caution the user to wear Nitrile gloves. Latex gloves don't afford enough protection. Are the people who make those statements merely being over cautious?

[steve simmons]

Many people who claim a staining developer makes no difference use T-Max and assume that film is representative. It is not. Use a real film such as FP4+, HP5+, Tri-X, etc. and I defy the printer with a sensitive eye not to see the difference.

It frequently appears to me that those who poo-poo a staining developer have built a career selling prints without it and do not want to admit there may have been a better way than what they've done. Others sell some type of competing products.

As for the toxicity many people develop a reaction to metol and can no longer place their fingers in a metol developer. All photo chemicals need proper ventilation. If handled carefully staining developers can be used safely.

steve simmons

[Mike Troxell]

I always wear Nitrile gloves when mixing or using pyro. I also wear a respirator when mixing chemicals for pyro. In my opinion, anyone who doesn't at least wear gloves when using ANY darkroom chemicals is taking a big risk. So why is pyro singled out? It seems to me that most of the people using pyro are safer than the people who stick their bare hands in D-76 or whatever, simply because the pyro users seem to be more aware of the dangers. Its a matter of being careful, no matter what you use.

[Jorge Gasteazoro]

Well Eugene I am not a toxicologist so all I can give you are my "educated" guesses as a chemist and a person who worked in hazardous waste disposal field for most of his career.

Once again, let me use hydroquinone as an example. From my previous post, you can see that pyrogallol has one more hydroxyl group than hydroquinone, this would make the molecule bigger. From what I understand and the little I know about biology and the skin barrier, it seems that the conditions necessary for diffusion through the skin are size and electrical charge. It could be possible that pyrogallol by virtue of it's extra hydroxyl group diffuses through the skin faster than hydroquinone, yet I doubt so, and if so, I doubt that it diffuses much faster than hydroquinone to make a big difference.

Some people report that as soon as they place their unprotected hands in a pyro developer they get a "taste" in their mouth. This is an entirely different thing, some chemicals attach to your taste receptors more readily than others, but that does not mean the one you cannot taste is not in your blood stream. The same goes for catechol, it has a "stronger" odor than pyrogallol, yet this does not mean it is more harmful, it only means your smell receptors are more attuned to this chemical.

Many of us develop silver prints in Dektol, which packs a wallop with Hydroquinone, yet nobody is warning us about it. As I said, all I can give you are my suppositions, but then these my be big suppositories...:-) you draw your own conclusions, me, I believe the toxicity claims are far more exaggerated than they are in reality.

[Jorge Gasteazoro]

BTW, this does not mean I advocate being sloppy in the DR, only that given proper care, IMO pyro is no more toxic than many of the other photo chemicals and given the concentration in which is used it is probably less harmful than Dektol.

[Kevin M Bourque]

Hi Steve –

I don’t want to speak too much for Howard, but he’s generally not in the poo-poo business. In fact, he’s quite eager to embrace techniques and technologies that make his pictures better. For instance, he’s a big fan of unsharp masking, which he learned in his sixties. He’s a fair and honest evaluator, and a very competent darkroom technician. If pyro made a significant positive difference in his pictures, he’d be all for it.

I remain unconvinced about pyro myself, but I’m willing to have my mind changed. Who has done the same test as Howard, exposing the same film to the same subject developing in two different developers? Most of us won’t take that trouble.

[Doug_3727]

Well...This has been a very intertaining thread. Seems to me the people who don't try or like Pyro have not tried it on more than tmax. If tmax is the only film you ever shoot then you should probably never use pyro. That just leaves it for the rest of use to use and benefit from its particular characteristics. As far as toxicity is concerned if you don't put your hands in it you won't have to worry about it. Wear gloves for god's sake. Other than that it is probably no more life threatening than a hamburger at McDonalds. People are dieing every day from cancer and a 100 other really nasty things, yet I have not heard of the first death from the dark room chemical headlines. Wise up. Be carefull and try all the developers you can get your hands on. This is a art form and by trying new things we expand our creativity. Hope this is not too far to the left for everyone. Its just that I have found pyro to be the best developer I've used yet. Good luck all.

[Brian Ellis]

"Seems to me the people who don't like or try pyro have not tried it on more than T Max."

I did all my pyro testing with HP5+. Another friend who was testing at the same time did his with some other film, which one I don't now remember but it wasn't TMax 100 since we were working from Gordon Hutchings' book and he recommends against using TMax 100 as I recall. We both reached the same conclusion as Howard Bond. As have others. If I recall correctly, Michael Smith posted a message here a while back saying he saw no benefit to PMK and I doubt that Michael has ever used TMax 100.

None of which is intended to suggest that pyro is no good, only that TMax 100 hasn't been the exclusive film tested by those who have found no benefits to pyro (or, more accurately in my case, to PMK).

[Ken Lee]

"Seems to me the people who don't try or like Pyro have not tried it on more than tmax. If tmax is the only film you ever shoot then you should probably never use pyro."

Interestingly, while TMax 100 responds very little to Pryo, TMax 400 responds beautifully, giving a film speed of 320.

[sanking]

"If I recall correctly, Michael Smith posted a message here a while back saying he saw no benefit to PMK and I doubt that Michael has ever used TMax 100 ........... "

Michael Smith does not use PMK but he definitely uses Pyro, ABC Pyro to be specific, same thing Weston used, though Michael's dilution is slightly stronger.

[Gary Samson]

I was very disappointed with the Pyro article by Howard Bond. His view point was very narrow and onesided and he continued to promote the myth about Edward Weston contracting Parkinson's disease because of his use of Pyro which has never been proven and which has been refuted on several occasions. The article did serve to support his view that unsharp masking-a technique he has advocated for years - is superior to to the use of Pyro. Unsharp masking is not going to be a technique employed by photographers who make contact prints from large negatives, shoot 35mm and 120 roll film or use a variety of large format films (Tri-X, EFKE, FP4, HP5, Bergger etc.) and print on variable contrast paper using split filtration. Those of us who have had the experience of printing a properly exposed and Pyro developed negative on variable contrast paper or Kodak Azo paper recognize the unique quailties (sharpness, tonality, fine grain) and ease of printing that Pyro developers afford. I hope that Photo Techniques will allow space for a rebutal to Mr. Bond's claims. There are not many of us shooting only 5x7 T-Max and making 2x and 3x enlargements.

[David A. Goldfarb]

Michael Smith is also contact printing on Azo, so the grain masking advantage of PMK is not really significant, while the increased density range and sharpness of ABC at the expense of grain is particularly significant. I used to use D-76 and PMK for Tri-X and found I got much better negs for contact printing on Azo with ABC pyro, though I prefer PMK for smaller format Tri-X negs that I plan to enlarge.

[Francis Abad]

Efke PL100, Pyrocat HD, and AZO - easiest combination. And you do not even need a darkroom!

[Michael Kadillak]

It is really humerous that rhetoric has such a pervasive root in our society. If pyro were not "adding" something to the final product, I would find it nearly impossible to believe that it would be more than a passing fancy.

Fact is that pyro has been around for a hell of a lot longer than most of the current "packaged" offerings. If you are one that is happy with the standard materials and the images that they create, by all means leave pyro alone.

If however, you are going to give it a "go" either journalistically or practically, at least be fair and use a sufficient film sampling to make an honest comparison. Only then will you know what it can do for you.

Cheers!

[Andre Noble]

Even though this is the LF forum, I want to note my first test ever with pyro was recently shooting a high contrast scene (white church, clear suuny sky) on six different traditional 120 roll films and developing them in Wimberly WD2D+, and enlarged onto Ilford MG IV. The results were immediately clear. I had never until that moment been able to print with such superior highlight gradation. I had been struggling with the bright Southern California sun and burnt out highlights in all outdoor shots for 7 years. Wimberly pyro made these negatives print so beautifully and so easily that I'm glad I stuck to photography. Highlights had become my achilles heal. Wimberly pyro did not just give better highlight control but rather the difference was a revolution in highlight control/gradation.

The key to effective WD2D+ use is to first find the effective film speed (I found it to be slightly less than half the box speed) and to really agitate for the 50% of total development time Wimberly suggests in the instructions that come with the Photographer's Formulary packaging.

In my experince with 120 and 35mm format, Pan F (rated @ 20 ASA) , FP4+ (@40 ASA), and APX 100 (@40 ASA) become superior films in WD2D+ for outdoor situations under direct sunlight.

[jerry brodkey]

I don't understand why people don't believe that T-max 100 doesn't stain well with pyro. I just posted the following in answer to another question. Here it is in case you missed it: ______________________________________________________________________________

I would like to clear up a misconception about T-max and pyro. Here are some recent results. The same scene was taken with 2 films of 5X7 T-max 100 shot at ASA 64. The SBR was only 5. The film developed with T-max RS 1:9 for 8 minutes at 75 degrees had a fb+f of 0.11 and a density range from .22 to 1.65. The sheet of film developed with pyrocat 1:1:100 at 75 degrees for 8 minutes had an ortho fb+f of 0.07 with a density range from 0.16 to 1.07. Using a 361T densitometer set to measure uv, the fb+f was 0.23 with a density range of 0.33 to 1.63.

I haven't printed them yet but they both should do well in Pt/Pd.

I should add that my solution B of pyrocat was a 100% solution rather than a 75% solution, thanks to Photographer's Formulary.

I think that it is a misconception that T-max doesn't stain well with pyro. In fact my first attempts with T-max and Rollo Pyro gave such bullet proof negatives that I never went back to the Rollo Pyro. That is when I started using T-max RS with John Sextion's published numbers and have been generally quite satisfied with the negatives it produces.

Jerry

[sanking]

Jerald,

You wrote: "The sheet of film developed with pyrocat 1:1:100 at 75 degrees for 8 minutes had an ortho fb+f of 0.07 with a density range from 0.16 to 1.07."

This is not correct, right? I can not understand how Pyrocat-HD 1:1:100 gave this much less density range than T-Max RS (.22 to 1.65.)

[jerry brodkey]

Sandy,

One can hold up the two films up to light and it appears that the pyro developed negative is just seemingly alot "thinner" than the RS developed one. I'm certainly happy with its development because of the good density range that I get with uv testing.

What I can not understand is why people say that T-Max 100 doesn't stain well with pyro.

Jerry

[Brian Ellis]

Sandy - I know that Michael Smith doesn't use PMK. I didn't say he did. His statement here or in the other group was that he saw no benefit to PMK but thought there was a benefit to ABC. I also know from attending his workshop and from his writings that he uses ABC. I didn't say anything about the benefits or lack thereof of ABC, I've confined my statements about pyro to PMK because that's the only form of it with which I have any experience.

[sanking]

Jerald,

Are you aware of the fact that the coating of current generation Tmax 100 film has a UV filter than eliminates a very high percentage of UV radiation in the 350 nm to 420 nm range? The result of this UV filtration, which amounts to about log 1.0, or over three stops, is that exposures for Tmax 100 negatives are much longer with Tmax 100 negatives than with other films.

[jerry brodkey]

Sandy,

I'm quite aware of that problem. Actually when Kodak announced that it was no longer going to supply Tmax 100 in 5X7 size, I found a dealer who had a stash and basically bought a lifetime supply of the stuff. I keep it frozen and will probably have to leave some in my will. :-) I'm doing more and more 11X14's and that has created a problem trying to find a decent film-developer combination. I think PL100 with pyrocat may be the answer and I'm into my first box now.

wrt a developer for Tmax 100, I'm not sure that pyro is any better than RS for contact printing onto Pt/Pd. I'll have to see, but at this point I have been quite happy with the results with RS and wouldn't know what to wish for with a new developer.

Jerry

[Bill Bartels]

To all: I stopped reading the how to magazines long ago. I do read the Azo forum because it has good info on the tools that I use. What Howard Bond or any other photographer thinks of a particular film dev. combo is pretty much meaningless. I think you must do you own testing and draw your own conclusions to see if it fits into your own way of working. For me and many others, shooting with an 8x10 camera, developing the negs. by inspection in pyro and contact printing on Azo paper is the system which I have been using for four years now. These tools allow a clear vision and most direct route to the finest prints I have been able to make. I love being able to go into the darkroom with a new neg. and have a finished print in 30 to 45 minutes with very little if any dodging and burning. I would never want to slave over a negative for hours,days or weeks to get a good print. I am sure that unsharp masking, split filter printing and other such techniques must work for some but I am glad I don't have to resort to such tools. This is my personal system and I'm stickin to it. Common sense rules when using pyro or any other chemicals in the darkroom

[sanking]

First, I apologize in advance for the long post but the issues are fairly complex and I want to make sure to cover those things that I consider most relevant.

I have not read the Bond article yet but I think it fair to say that reactions to it have been pretty much predictable. Folks who believe in the superiority of pyro developers question Bond's motives and methodology and those who don't see it as proof evident that they were right all along and that all the talk about the superiority of pyro is just myth.

The original report on this article stated that Bond found PMK and D76 comparison prints to be identical in terms of sharpness and nearly so in terms of tonal range. I would like to respond to those finding, but first three comments.

1) I will try to be objective in my comments and simply state what I know to be facts and I hope that what I say will be received in that light. It is true that I personally believe pyro developers, specifically Pyrocat-HD, offer a number of advantages in my own work. However, I am not dogmatic about the issue and will willingly concede the use of pyro is not absolutely essential to the production of high quality images, and have so stated at my times in the past.

2) My approach to evaluating films and developers is based three steps: a) Learn as much as possible about the characteristics of the materials in order to have a global understanding of the issues, b) apply this information with controlled testing, and c) validate or reject the conclusion suggested by laboratory testing with work in the field. It is certainly true that the final photograph is the thing we hang our hats on, but bear in mind that any one test is valid only for the particular set of circumstances of the test so it really pays to understand the issues.

3) I have no financial interest in promoting the use of pyro. My Pyrocat-HD has been published in print and is available on various web sites, and I am not involved in the distribution commercial marketing of the product.

OK, let’s discuss tonal issues first. The report on Bond’s article notes that he found that the pyro negative and D76 negative gave almost identical tonal range and “that a little extra work would make them identical.” Sorry, but this is simply not possible with variable contrast papers. The reason is very simple. VC papers have two different coatings, one primarily sensitive to blue light, the other primarily sensitive to green. These two layers have an equal response to non stained negatives. They have a different response to stained negatives for two reasons: 1) the color of the stain affects the two layers differently, and 2) the stain is proportional, most in the areas of high density. This fact provides a kind of compensation that would be virtually impossible to duplicate with non stained negatives. You could in theory duplicate the compensation with non-staining developers for one type of lighting condition, say with subjects of very high contrast, but that compensation would give unacceptable results with subjects of less contrast.

2) About sharpness. It should come as no big surprise that Bond did note observe any difference in sharpness in his comparison prints since he is after all working with a fairly large negative and any differences in sharpness on the negative would be minimized by the enlargement ratio.

However, there is no question at all in my mind that some pyro developers give sharper negatives than D76, either straight or 1:1, assuming appropriate development. Whether this increased sharpness on the negative transfers itself to the print is another issue, but since the weakest link in the printing chain is the one that fails first I think it is smart practice to always make the sharpest negative possible, so long as other pictorial qualities (smoothness of tone, grain, etc.) are not put at risk. Assuming your objective is to make prints of maximum sharpness, of course. But you ask on what do I base this contention? The answer is a lot of specific comparison testing of D76 1:1 and Pyrocat-HD with many different films.

But first, what is sharpness. Sharpness is an impression of image clarity and is influenced by many factors, of which the most important are resolution (lines visible) and acutance (boundary definition). Resolution by itself is not a reliable method for determining image quality since as it turns out some low resolution systems appear to give results that are superior to high resolution systems, but resolution plus acutance provides reliable results. Of course an even better indicator of sharpness in optics and image systems is the modulation transfer function test, or the MTF, but this kind of testing is not available to most of us.

In practice, however, I have found that in testing both optics and film that when resolution tests are made so that the comparison negatives are of the same contrast the result is in the great majority of situations a fairly reliable indicator of actual sharpness. Persons who understand the complexity of this issue will no doubt find flaws in this admittedly imperfect system of testing but in spite of such objections I will state again that in my own work resolution when comparisons are made at the same contrast appears to be a reasonably reliable method of testing for perceived sharpness.

The bottom line is this. I can not absolutely prove to you that pyro negatives are sharper than D76 1:1 negatives. What I can do, however, is prove that Pyrocat-HD (and I believe this would also be true for both PMK and WD2D+) gives better resolution, on the order of 10-20 lpm, than D76 1:1. If you don’t believe me test it yourself by doing this.

1. First, determine what time of development is need to develop the same effective printing contrast with the two comparison developers. You can do this with either a step tablet or with a densitometer. However, if you use a densitometer make sure that you take into consideration the actual difference between what you read and effective printing density.

2. Next, set up a standard resolution chart and with your camera on a tripod make a series of exposures of the chart, at least four for each developer. You could do this with virtually any camera system. I use a high quality medium format camera for my own testing because of the quality of the optical system but you could also use a large format camera provided that the lens is of sufficiently high quality. For your tests use a film capable of resolving over 100 lpm. In my case I use a 6X9 camera and make eight identical exposures on 120 film at a lens aperture of f/11, focusing on the ground glass.

3. Develop the film for the times previously determined to give the same effective printing contrast. In my own tests I cut the 120 film into two parts, developing one in D76 1:1, the other in Pyrocat-HD. Be sure to use the same method of agitation with both developers.

4. When the films are dry examine them at about 40X magnification and calculate the resolving power of the D76 and pyro negative. Since you used the same lens aperture and same roll of film for all of the tests you can be reasonably certain that any difference in resolution observed results from the developer, not the lens or camera system.

5. If you have access to a very high resolution scanner you could validate your observations by scanning the chart at maximum ppi, enlarging the results, and outputting to a printer. I calculate that this step would require a scanner of about 8000 – 12000 ppi. I tried this with my Epson 4870 but this scanner will not resolve as many lpm as are on the negative.

In conclusion, I recognize the limitations of this type of testing as they have already been pointed out to me by someone with extensive knowledge in the field. However, I am personally satisfied that the results do provide a reasonably accurate indicator of negative sharpness. The question of final image sharpness is of course another matter and I do not intend to address it here. It is sufficient for me at this point to know that Pyrocat-HD gives me sharper negatives than D76 1:1.

I welcome and expect reasoned comments on both the methodology and conclusions as herein presented.

[CP Goerz]

Didn't read the article either but were the prints Mr Bond made on VC paper? If so that kinda shoots a pyro neg in the foot a bit. For further reding on the subject I HIGHLY suggest Edge of Darkness by the recently(and very sadly) deceased Barry Thornton. Essentially the PMK pyro masks itself too effectively for use on VC paper. I use PMK on FP4 on graded paper..old school backattcha!! :-)

CP Goerz.

[steve simmons]

Hi Steve – I don’t want to speak too much for Howard, but he’s generally not in the poo-poo business. In fact, he’s quite eager to embrace techniques and technologies that make his pictures better. For instance, he’s a big fan of unsharp masking, which he learned in his sixties. He’s a fair and honest evaluator, and a very competent darkroom technician. If pyro made a significant positive difference in his pictures, he’d be all for it.

I remain unconvinced about pyro myself, but I’m willing to have my mind changed. Who has done the same test as Howard, exposing the same film to the same subject developing in two different developers? Most of us won’t take that trouble>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Howard is previously on record as stating that pyro offers no advantages over a non-staining developer. He also picked one film and apparently based on a single test states that pyro does not offer any benefit. If he wanted to do a truly objective test he would have sampled other films.

As for pyro's toxicity I suggest getting it in pre-mixed form. If you develop in trays as I do use surgeon's gloves. His claim that pyro caused Weston's Parkinson's desease is an old myth that has never been proven. He should have stated such in the article

I do not believe he entered the test with an open mind or really did anything scientific. He simply proved what he has already stated previously w/o having done any tests. Now he feels he has a test to prove an old claim.

steve simmons

[fred arnold]

Jorge, et al.,

As for the toxicity of Pyro, I checked the Merck Index, 12th Ed., and came up with the following:

Pyrocatechol: LD50, Mice: 260mg/kg, and some references to its carcinogenic faculties

Pyrogallol: LD50, Rabbit: 1.6g/kg (1600mg/kg), orally, all sorts of bad warnings (see below)

Hydroquinone: LD50, Rat: 360 320mg/kg, orally, mainly skin and eye irritation.

Metol: no LD50 or side effects noted.

Phenidone: Low oral toxicity, no cases of dermatitis known

With the exception of Metol and Phenidone, none of these are great about side effects (though a casual read of the Merck would indicate that Metol allergy is probably hydroquinone allergy). Pyro, on the other hand, is the only one listed as "Poisonous!", with the note that ingestion may cause kidney and liver damage, hemolysis, circulatory collapse, and death, and that these effects may result from absorption through the skin. The LD50 for injection/transcutaneous absorption in primates is not given. For the first three, the reader is referred to the 'Phenol' entry for further toxcitity data (which is extensive). It's definitely a wear a dust mask and mix with good ventilation chemical, especially if you're handling it in bulk.

Why it gets through is not discussed, but it is in a different toxic category than the others. The O-chems I talk to think that it's a "don't look at it cross-eyed" rather than a merely "don't put your tongue on it" specimen as well. Given that I probably have enough heavy metals left in me from grad school, and am showing some signs of a 'metol' allergy, I will admire pyro from a distance. In a proper fume hood, I wouldn't worry about it much; outside the lab I'd be a lot more wary.

[Francis Abad]

As far as contact printing on silver chloride paper is concerned, my TMAX 100 negatives developed in TMAX RS 1:9 cannot hold a candle to my Efke PL100 negatives developed in Pyrocat HD 2:2:100 (I use an already premixed liquid kit form to avoid handling any type of powder). Sure they are different films but I have developed some TMAX 100 negatives in Pyrocat HD and it stinks! I have binned all my TMAX negs, whether developed in RS or Pyrocat HD. For contact printing on AZO that film cannot build enought contrast to even allow the use of Grade 3.

[Tom Duffy]

I took a close look at the comparison photos in the Photo Techniques article. To me, even as published, there was an obvious improvement in shadow detail differentiation and highlight detail in the PMK print vs. the D76 1:1 print. In the masked print those differences were more obvious, still - perhaps too much so. I've never seen a masked print "in the flesh" so I can't comment.

I have, however, done my own extensive testing with 5x7 Tri-x enlarged to 11x14 on Bergger VCCB paper. I compared D76 1:1, Rodinal at 1:50, PMK and Pyrocat HD all processed in a Jobo at a motor speeed of "3". Both the PMK and Pyrocat were sharper to the naked eye, even at that degree of magnification, than D76 at 1:1. Pyrocat gave me better whites than PMK.

I really wanted D76 to "win", so I wouldn't have to mix my own developer and I wanted to avoid the use of pyro if I could; but the improvement in the print, using pyro, was obvious.

Finally, do you really want to create a mask for every negative you print?

Take care, Tom

[Jorge Gasteazoro]

It's definitely a wear a dust mask and mix with good ventilation chemical, especially if you're handling it in bulk



I dont know that I agree with you here Fred, looking at your data there are many things that come to mind. Lets start with pyrogallol...1.6gr/kg??? whoa...if you have a rabbit that weights 4 Kg, that is 7.4 grams dosage! this is the problem with LD50 studies, the dosages are so massive that they are many times misleading. We all remember the cancer warnings about saccharine, which we now know were misleading as the dosages the rats were given was unrealistic.



Lets move on to hydroquinone and pyrocatechol, here we have rat and mice, given the weights difference the dosages seem to be similar, with similar results.



I really doubt that a person mixing from bulk would inhale more than any of the dosages you posted, and even then, there is still the matter of lenght of time the chemical was given to the animals, I hope you will agree that breathing pyrogallol once every 2 months is much less harmfull than having it fed to you daily for a month. Unlike heavy metals, organic compounds are broken down and filtered by the body without harm given a small enough dosage.



WHich brigns me to my point, if you eat a burger king twice a week, that is more likely to kill you sooner than mixing pyrogallol and using it. Personally I use gloves when I develop in catechol and I have extractors in my darkroom which are on every second I am in there, this is just sound lab practice, but IMO the warnings given about pyro are exaggerated given the concentrations at which we use it and the lenght of time we are exposed to it when mixing it.

[Mark_3632]

Jorge,

COuld it be that the warnings are exagerated on purpose. Sort of for the same reason that there are warnings not to dry your hair with a hair dryer while in a full tub of water. There are people out there who are careless with their photo chemicals. I have worked with a few in college darkrooms. In fact one was banned for unsafe practices. I know I was extra careful while mixing pyrocat because of the warnings, and I am really anal when mixing my photo chemicals.

[Jorge Gasteazoro]

Mark, you know there is no such thing as a "fool proof" anything. As soon as you think you have it figured out, some idiot proves you wrong by doing something incredibly stupid.

I am just saying that given the concentrations we use in the developers and the amount and length of time we are exposed to it when in raw form are so small and short that for all practical purposes the risk is non existent. Let me give you and example, pyrocat stock solution is mixed 4 gr per 100 ml, that is about 4000 mg/kg if we fudge a little on density etc, you then dissolve this 100 fold to give you 40 mg/kg. I dont know the absorption rates of catechol but lets say you stick your hands in it for one hour and you absorb all of it (which clearly would be impossible or you would not be able to develop the film) at this point you are about 1/5 of the LD50 for a very short period of time, if you then stop and do not develop until next week, your body is more than capable of breaking down and handling this amount.

As a haz waste disposal chemist, I was always asked why I used so many precautions when all I was packaging was a little bit of the harmful chemical. My response was: " you might be exposed to this only a few times a year, that is no big deal, I am exposed to this on a continuous basis and the dosages are cumulative, I HAVE to do this in order to stay healthy"

It is the same here, a little exposure wont kill you, exposure on a daily basis to greater amounts will. It is all relative, to me the "warnings" about pyro on darkroom use are exaggerated, I bet you there is more pyrogallol in hair die than it is in 10 times the concentration of a developer.

Look at it this way, we have our own lab "rats", Gordon Hutchins has been using pyro for more than 20 years, I believe Simmons is also right up there, if pyro was "so" poisonous, I bet they would have serious health problems by now. IMO the 3 most important factors to judge toxicity are: concentration, length of exposure and route of contamination. The LD50, IDLH, PEL numbers are only guidelines that have to be read with an analytical mind, I have seen both, instances where people in a lab are overcautious (in itself not a bad thing, better be safe than sorry) and I have seen instances where supposedly smart people with degrees up the wazoo do some of the dumbest things.

Like I said, me, I use gloves and air extractors, but there have been times when I have stuck my hands in the developer and so far they have not shriveled and fall off...:-)

[fred arnold]

Jorge,

I'll probably concede you're right, though I'd still wear gloves when handling the solutions. My perspective, from being one of the people who used to keep you in business :), is that I'd probably worry more about getting the solution on my skin repeatedly than the occasional dust, and the Merck warnings are probably only relevant if you work with it in vats. This being said, from the skin straight to your blood stream will have a different effect than ingesting it where it can be partially broken down first. We look at photographers from that era; Strand and Adams lasted a good, long, time, Weston succumbed to Parkinson's, which may be genetic, or may be because of sensitivity to the chemistry he used. Unless someone wishes to help fill out the paperwork so that I can spill pyro solutions on grad students and observe the results, we'll have to go with "it's probably not too bad in the quantities you're using".

In all fairness, it's partly experience, and I worry more about organics that can transfer dermally than I do about the heavy inorgs, even though those drove me finally into Theory. I'll admit that the prints I've seen on older-style emulsions done with pyro, and contact printed are lovely (Adam's 16x20 of the aspens where you actually can see the worm-holes in the leaves comes to mind, though it was enlarged), but the paragraph-length warning about dermal transmission and toxicity after an entry that seemed to argue that you were going to have to eat pounds of it to be fatal has made me somewhat warier.

[sanking]

Jerald Brodkey asks, "What I can not understand is why people say that T-Max 100 doesn't stain well with pyro."

Turns out that I did some recent BTZS type testing with Pyrocat-HD of FP4+ and Tmax 100, using very fresh film (expiration date of 08-2006 for the Tmax 100, 01/2007 for the FP4+). Luckily I had in the tests a FP4+ and Tmax 100 negative that matched perfectly in terms of Visual (silver density) reading at Step 21, so to determine the difference in stain all I had to do was measure the same step on the two films in Blue mode (which measures stain plus silver density). Turns out that the two films produced virtually the same percentage of stain density.

So Jerald poses a good question. Why are so many people saying that Tmax 100 does not stain well with pyro?

[Pete Caluori]

Greetings,

I too have not read the article yet, but would like to share some information from a recent printing session, which I believe confirms Sandy King's statement: "Sorry, but this is simply not possible with variable contrast papers."

I have a 8x10 TMY negative that was developed in PyrocatHD for the purpose of printing alt process. It is developed to a very high contrast and prints beautifully as aVan Dyke and Albumen print. Yesterday, I was making some quick contact prints on conventional VC RC paper (Ilford Multigrade IV RC warmtone) and decided to print this negative. Having done a similar exercise with a non stained negative (Xtol) I would have to dial in 100+ units of yellow filtration, but this negative printed beautifully without any filtration. The only explanation is the pyro stain.

For those interested, this negative has blue channel readings of Fb+f = 0.36, Dmin = 0.46 and Dmax = 2.70. A negative with these densities developed in D-76 would never be a "straight" print on unfiltered VC paper! Pyro does make a difference.

Regards, Pete

[Jorge Gasteazoro]

though I'd still wear gloves when handling the solutions.



Jerald, this is a very sensible thing to do, I do the same! Look, perhaps it seems I am advocating being careless with the stuff, I am not! All I am trying to say is that the "toxicity" alarm should not prevent someone from trying the developer, as it seems it has done with some people. Sadly I think the damage has been done and you cannot put the tooth paste back in the tube. I have read here and in other forums people stating that they will not try pyro because it is too toxic. This desicion based on ill presented information, mostly due to a book written by a woman who had very little practical knowledge and in most part was regurgitating the Merck index.

All I am trying to say is that if someone wants to try pyro and uses basic cleanliness procedures nobody is going to die nor will their house be declared a superfund site. BTW the same precautions should be taken with ALL developers, not just pyro or catechol.

Sandy, you bring a good point. At the time I tried Tmx 100 with PMK I saw very little stain, but I only had a b&w densitometer so I could not read the stain. My conclusion was that Tmx 100 did not stain well, compared to tmy or delta films, but this was a conclusion reached by eyeballing the neg, not making any measurements, if you are getting the same stain with 100 tmx and fp4, well then that is darn good eveidence that 100 tmx stains very well.

[David A. Goldfarb]

Just to clarify my own position on TMX and PMK, I've never said it doesn't stain, but rather that I didn't see any particular advantage to using PMK with TMX. TMX is already a fine grained film, so grain masking isn't really necessary, and it has a fairly straight line curve, so when I tried it, I didn't see that much of a change in highlight separation or any of the other effects generally associated with pyro, and which I do see with Tri-X. Maybe Pyrocat-HD produces more interesting results than PMK with TMX, but I don't see any real attraction to using PMK over D-76 (1+1) with TMX.

[Michael Mutmansky]

Sandy,

I haven't tried TMX in Pyrocat or Pyro, but I do have a thought on why people may dismiss this film as unsuitable for a staining developer. I think many people associate a fairly high non-proportional stain with staining developers, and a film that has very little or no non-proportional stain is dismissed because the most obvious visible evidance that a staining developer was used is missing.

Consider that many people were performing a post-develop staining dip after the negative was fixed. This step was recommended in the PMK Bible, and many Pyromaniacs are fundamentalists (literalists) with the ideas put fourth in the Bible. It's apparent that the purpose of this step is to increase the stain, but unfortunately it increases the stain indiscriminately over the entire negative, yielding excessively high B+F stain and contributing nothing to the image portions (except an equal increase in density).

People who print alt processes learned fairly quickly (if they made an effort to think about it) that post staining is a useless step, and is detrimental to the printing process with the very insensitive materials as we use. Silver printers seemed to take a bit more time to learn the lesson, simply because they can print through B+F stain without too much difficulty. Now, I believe that the post stain step is not recommended anymore by Gordon (is that correct?).

Pyrocat is a developer that has a more brownish color to the stain (as you know), and it is easy to not see the stain in the proportional areas of a negative because the color seems to be more easily hidden in the density of the silver. However, the color is fairly easy to see in the B+F area, unless there is little or no staining of the B+F area.

The interesting thing is that the IDEAL stained negative has at least a proportional stain, or possibly even better, superproportional stain with silver density. I've not used many different pyro/pyrocat formulas, but I know of none so far that have even a proportional stain response curve to the silver density. As we have seen, Pyrocat can be one of the best, with only a slightly decreasing proportional curve to density. I believe many of the other developer formulas have a much greater negative slope to the stain response curve, which results in more B+F stain, and lower stain proportionally up the density curve.

What I'm suggesting is that TMX may actually be a nearly IDEAL film for a pyro developer, because is has an inherent low staining effect, and it may result in a more proportional response to the silver density. It may require a different formulation of developer to increase the stain response in the film, but that is a simple matter of trials to determine. I'll leave that to someone else to explore, as I've got my hands full with my own pursuits.

My initial tests with Acros in Pyro seem to indicate that it is similar to TMX in this respect. It appears to have a very low B+F level, and a nice linear response curve. Because of the low B+F stain, it looks like a normal negative, until you compare it to a truely normal negative, in which case the difference is obvious.

David,

I suggest you stop enlarging for a while, and start contact printing. Give that a year or so. When you go back to enlarging, the grain will be obvious, and you will try anything you can to reduce it. That is, if you are a discerning printer. I just suggesting that the issue here has to do with perspective and expectations. If your methods satisfy you, then there is no reason to be changing them. But there is also no reason to spend time dissuading others from finding their own path.

---Michael

[David A. Goldfarb]

Michael, I do contact print as well as enlarge and have been doing so for some time, and I agree that I always prefer a contact print to an enlargement, but not all the photography that I do lends itself to working in 8x10" or 11x14", so when I shoot 4x5" or smaller, I enlarge, and I usually shoot Tri-X processed in PMK or Acufine if I need the speed. For contact printing I shoot Tri-X or Ektapan (until I run out) and process usually in ABC. Occasionally I shoot TMX and process in D-76 (1+1), usually for fine grain in smaller formats or in 8x10" with scenes that have a very wide brightness range.

Efke PL100 looks like it's becoming another standard for me in PMK for enlargement, ABC for contact printing, but I haven't been using it long enough to say that I'm committed to it.

[sanking]

Michael wrote:

"People who print alt processes learned fairly quickly (if they made an effort to think about it) that post staining is a useless step, and is detrimental to the printing process with the very insensitive materials as we use. Silver printers seemed to take a bit more time to learn the lesson, simply because they can print through B+F stain without too much difficulty. Now, I believe that the post stain step is not recommended anymore by Gordon (is that correct?)."

I have never recommended the post stain for Pyrocat-HD. It does nothing but add a general stain that has the same function as B+f stain and is in my opinion a totally useless waste of time for all processes, silver or alterntive. Fortunately for silver printers the post stain does not in most cases do any harm except adding some extra time to priting exposures. On the other hand if you happen to be working with film that has a high B+f base from either aging or conditions of storage the extra general stain could result in a loss of N+ expansion possibilities, even for silver printers.

For alternative printers a high level of non-proportional stain will add significantly to exposure times so we want to avoid it whenever possible.

I have heard from people who attended one of Gordon Hutchings' workshops last summer that he does not recommed the post stain step any longer. But I think the recommendation is still in his book and there are apparently a lot of people who continue the practice.

[Paul Metcalf]

What say all about the hardening effect of pyro? Isn't it like other tannins used to harden, or tan things, like leather (and most black teas!)? What impact does this have on printing, if any? Also, does a post fix bath of just sodium metaborate contribute to stain and hardening (without the overall stain as I found when using used developer)? It's hard to tell if staining continues post initial development as it's a bit messy to try and use a densitometer on a wet negative. Visual inspections are often misleading for me due to "expectations."

An interesting thing to do is to completely bleach out a pyro negative and non-pyro negative, then re-develop in pyro, and print. You really see what's happening with the silver content in the original development when you do this.

My problem I had (have) with TMAX is I never consistently got Zone III placement. Sometimes I did, other times I didn't. The EV I was metering to should have placed it there consistently (using same development) but it varied. Almost like there's something else that impacts this film (amount of UV light or color of light maybe?). I haven't experienced the same (in fact, the complete opposite) with FP4+ in PMK. If the EV says it's going to be Zone III, by golly, it's Zone III. So far same with new Tri-X in PMK.

[Kirk Gittings]

AS many of you know, I have only recently started participating in this forum and frankly overall I am greatly impressed with the knowledge and generosity of people participating, but Jesus what is the deal with any mention of Pyro. The congressional record debating the merits of Mapelthorpe is not as passionate.

[Kevin Crisp]

Interesting discussion, with strong opinions, as usual. So why doesn't someone take Bond up on his offer:

[He ends that article by asking to see similar pairs of prints that show a substantial difference between pyro and any other developer.]

[Jorge Gasteazoro]

Kevin C, you do have a point! I just bought a couple of 120 plus x rolls ( the only ones I could find here in Mexico) I think I am going to develop one in pyrocat and one in HC110 and see what happens. I will let you all know next week.

[Kevin M Bourque]

Glad to hear it, Jorge!

It is likely that straight prints from your two test negatives WILL be different. The key will be to match the scales of the two prints using appropriate filtration.

I had done a similar test about a year ago and found the differences to be subtle, at best. When I matched the contrast (using VC filtration), most of the differences seemed to disappear.

Good luck. Let us know how it goes.

[Jorge Gasteazoro]

I disagree Kevin, if you develop both negatives to the same CI to match the paper scale a work print made on the same paper grade should show which negative is easier to print. The idea is to show which developer produces the easiest negative to print. Anybody can mak two prints look the same depending the amount of effort they put into it. If I make a work print with no darkroom manipulation and one looks better than the other then that will show that the corresponding developer is better, or produces better negatives.

[Kirk Keyes]

Jorge,

I've always been curious about determining the CI on a pyro neg - do you use the blue channel CI, the green channel CI, the visible channel CI, and average of the blue+green? I get a different CI from the same neg when comparing the blue and the green - blue has a higher number. It would make a difference when using VC papers?

Also, for general information, I did find that the new 100TMX stains much better than the old TMX100 and with a lower b+f value.

Kirk

[sanking]

I have finally had an opportunity to read Howard Bond’s article “Pyro Investigation” in the May/June 2004 issue of Photo Techniques and I am really greatly under whelmed by his “investigation” and conclusions. The article attempts to make three points.

1. Comparison prints made from D76 and PMK negatives of the same scene do not appear to show any greater ability of the pyro developer to hold details in the greatest highlights.

2. The comparison prints at 4.5X magnification look equally sharp.

3. The use of pyro developers may cause Parkinson’s disease.

Item #1 shows that Mr. Bond apparently did little or no research before conducting his tests. I say apparently because in the absence of any mention of filtration in making the comparison prints one must assume that he used graded papers for the tests, which suggests he does not even understand the nature of the issue. The claim made by Gordon Hutching for the ability of PMK to hold upper highlight values without compressing shadow values is based on the use of VARIABLE CONTRST papers, not graded papers. Anyone who wants to understand the issue better should consult both Gordon’s Book of Pyro and/or my article on pyro developers at http://unblinkingeye.com/Articles/PCat/PCat3/pcat3.html. The use of graded papers by Mr. Bond renders this part of the test useless and a waste of time. He spent his time disproving what no one who really understands how pyro developers work has claimed, i.e. e. that you can get highlight compensation with graded papers.

Item #2 is more complicated. Sharpness is a perception of clarity and is quite subjective, therefore in the eye of the beholder. However, at 4X magnification we would expect any differences in sharpness to be very subtle and the subject chosen, a natural scene set a considerable distance, is totally inappropriate for the evaluation of sharpness. A much better scene would have been one with a lot of textured man-made objects, such as distance views of brick buildings, signs in the distance, textured foliage, trees against the horizon, etc. Finally, Mr. Bond notes that the D-76 print with an unsharp mask was much sharper than the pyro negative printed straight. Duuuuh!!

On Item #3 I don’t have much to add to previous comments by Jorge. But I will remark that I consider Bond’s comments on the dangers of pyro to be typical of what we see in most popular publications: inadequate and selective use of research and shameless fear-mongering.

Mr. Bond is without doubt a very fine photographer. In my opinion he should stick to what he does best without getting into thesis “investigation.”

[Jorge Gasteazoro]

Kirk, I use the blue channel exclusively. If you use the red channel you get the silver density, the green gives you in between numbers and the blue is the one that has the highest and most accurate. But then I use a x rite 369, which has a blue light for both vis and UV, it is not a color densitometer. When I was using an x rite 810, I got the same results you mention and always based my testing on the blue channel.

Now here I am going to paraphrase Phil Davis, I asked him why he did not recommend the BTZS for stainning negatives. He had a two part objection, one that he was not sure the stain was constant from developing session to developing session. This might be a problem with developers like PMK or even WD2D where the overall stain might change depending on an after bath, etc. It is not a problem with Pyrocat HD, since it is a proportional stain developer, there is very little stain the the shadows, and the stain seems to be constant.

The other objection was that he was not sure of the spectrum of the blue light. IOW how blue should be the light in the densitometer. With the 369 densitometer I use, I have gotten very good results obtaining accurate speeds and development info. Seems whatever the 369 or the 361T use for vis and UV is a good wavelenght.

If you are working for silver the blue channel should give you pretty accurate results.

[Kevin M Bourque]

Jorge –

I wanted to encourage you to do the test you described. Most people will not take the trouble.

Here was my methodology. I developed the two rolls of film (same scenes and exposures) but didn’t especially try to match them by development. I have a densitometer but pyro is well known for fooling densitometers that can’t read color (mine can’t).

I got a printed high value I liked from pyro neg and then let the rest of the values fall where they might. Then I adjusted the contrast of the D76 print (with filters) until the same high and low matched in the print. As I recall, the D76 negative needed about 20M to match the pyro neg.

I decided that there wasn’t much real difference between the two prints. They weren’t identical, but it was not obvious that one was better than the other. The differences were subtle and may have been simply errors in my ability to exactly match the contrast.

I also tried burning some highlight areas. There was no effect with the pyro neg I couldn’t match with the D76 neg.

Since it’s your test, please conduct it as you see fit. I just wanted to lest you know what I had done. I didn’t try to decide which one was “easier” to print since that is a highly subjective quantity and might change from negative to negative.

Good luck!

[sanking]

Jorge,

Are you abel to take Visual readings with your X-Rite 369? If so I suggest that you get a 47B filter and use it in Visual mode for evaluating effective negative printing density for Variable Contrast papers. Blue mode will work fine for graded papers but VC papers have sensitivity to green light in the low-contrast layer and the 47B is a broad band filter that allows quite a bit of green light to pass.

To make the measuremnt just place the 47B filter over the meauring aperture and null you densitometer to zero, then take the readings. Your readings with the 47B filter will be consistenlty lower than than with the densitoimeter in Blue mode and provide a more accurate idea of effective printing density than Blue mode unadjusted.

[Jorge Gasteazoro]

Kevin, I understand but I think you made the same mistake in evaluating the developer as Bond did. IMO I think Sandy has it right, he is fond of saying that all developers will work to 95%, it is that extra 3% that you can squeeze from the better developers that make the difference.

The magazine has not come out here in Mx yet, so I have not read the article, but from Sandy's comments I can see where are the problems with the comparison.

For one, an accomplished darkroom printer can grab an absolutely horrible negative, make contrast masks, sharpening masks, bleaching, etc, etc. and make a great print, but what is the point of this? I think the capabilities of a developer are shown in the ease of making a good initial print. Funny that Bond admits in his article that with a "little more work" D76 is just as good as pyro....well duh! Of course! but that is the main point I think Bond is missing, we or at least I are looking for negatives that require the least amount of darkroom manipulation to produce a good or great print.

Sandy, I also have a color densitometer which can read on the green channel. I agree with you that the stain is more relevant with VC papers, but it should also have some importance when printing with graded paper. In my comparison of Pyrocat HD, PMK and WD2D, all three developers had beautiful clouds that printed beautifully in grade 2 paper with no effort whatsoever. All 3 prints were made with no manipulation and all 3 showed great separation in the clouds. This was a shot of a chapel in full sunlight with an SBR of 9. I seriously doubt that d76 or hc110 would have been able to handle the same separation in the highlights even if developed to the same CI.

I dont know, I will see if I am wrong.

[Francis Abad]

I must have taken it for granted but Jorge makes a very good observation - using Pyrocat HD does almost eliminates the need to burn the sky in to get the clouds to come out. Funny that I forgot how much burning in of sky areas I used to do before using Pyrocat HD.

[Kirk Keyes]

Sandy,

You recommended to Jorge and his Xrite 369: "If so I suggest that you get a 47B filter and use it in Visual mode for evaluating effective negative printing density for Variable Contrast papers. Blue mode will work fine for graded papers but VC papers have sensitivity to green light in the low-contrast layer and the 47B is a broad band filter that allows quite a bit of green light to pass."

I also agree that the green channel must be taken into account when using VC papers. With graded papers, it should not really matter if you use a green or blue or vis channel, as when you do the testing, you will empirically find a CI that works for your materials - the bias of the densitometer readings in any particular channel will be self correcting.

But we we start sharing data - densities, CI, development times... - it becomes much more importnant that we are doing very similar proceedures to make our measurements. By suggesting to Jorge that he use broader band filter, you are suggesting that he use wavelengths measured in both the blue and the green channels.

So that brings my point back to which channel is really best for pyro negs. Or perhaps as you indicate and I belive it should be a combination of the blue and green. What I do is graph out my CI for Blue and Green onto the same graph of Time vs. CI. I then take the average of the two lines and develop for the CI I want. Essentially averageing the two sets of reading.

I'm using a Noritsu DM-210 that has RGB and I find the PMK has a quite repeatable stain and it is proportional to the silver density as measured with the green channel. Jorge, I don't understand Davis' concerns... I use a Jobo and I don't use the developer afterbath as that always seemed like a bad idea to me since I read about it in the Book of Pyro over 10 years ago. Perhaps Davis didn't want to modify his program to take the stain into account.

(Also for future reference, Kodak calls the 47B a "Deep Blue" filter - Edmunds Scientific has a graph of the color separation filters online, and it shows the 47B as haveing a narrower bandpass than the 47. Perhaps you have their properties reversed or Edmunds got thier graph wrong?)

Kirk

[sanking]

"So that brings my point back to which channel is really best for pyro negs. Or perhaps as you indicate and I belive it should be a combination of the blue and green. What I do is graph out my CI for Blue and Green onto the same graph of Time vs. CI. I then take the average of the two lines and develop for the CI I want. Essentially averageing the two sets of reading."

Blue mode is best for graded silver papers. For VC papers Blue suggests too much contrast, Green too little, so reality is somewhere in between. Exactly where may vary with papers but my experiences is that the correct reading is about 2/3 of the way from green toward blue, which is not that different from your procedure of taking the average of the two lines.

I think you are probably right about Davis not wanting to modify his program to take the stain into account. This is one of the reasons he avoids PMK. Another is the fact that some people have not gotten good results with PMK in the BTZS tubes that he originally introduced.

Finally, you are correct in that I reversed the characteristicss of the 47 and 47B, and I apologize for any confusion this may have caused. The 47B is indeed the narrow band filter, and the 47 is the one that allows some green light to pass.

[Jorge Gasteazoro]

Perhaps Davis didn't want to modify his program to take the stain into account.



Kirk, is not that. The BTZS program will work with the stainning developers. Part of his objection is that if we are to use the maximum presicion allowed by the process, it does not make sense to introduce variables that are not constant at some point.



As to the stain, I develop by brush, which along with drum porcessing produces the best eveness in negatives, and I did notice a difference in stain between the test negative and the step wedge negative for wd2d and pmk. This is without a pre or post bath, no presoak etc. The difference was not great enough to make a noticeable difference when printing, but it was there.

[Kirk Keyes]

Sandy, Jorge - thanks for the quick replies!

Sandy - so you suggest biasing the b to g reading by abs = (2xblue + 1xgreen)/3 ?

I haven't used the BTZS tubes (or software). I use a Jobo Expert and I am happy with repeatability. Do the BTZS tube have issues with constant agitation with PMK, or is it just from non-constant sgitaion schemes?

Jorge - does the BTZS software work with blue/green channel info, or are you saying you can use it when the data are averaged or combined as above?

And which variables aren't constant? I find the staining of PMK very predictable. (Sorry, Sandy, I haven't gotten around to trying Pyro-Cat yet. I did buy some pyrocatechol though!)

Kirk

[Jorge Gasteazoro]

Kirk, you input numbers, so you can choose to do curves with the green values, or with the blue values or an average. There is not an specific "blue" curve, or "green" curve. All it does is plot the points and give you the appropriate analysis.

I have seen instances where PMK varies in stain intensity depending on the water you are using to wash it. If you are getting constant results, good for you! All I am saying is that one has to take this into account.

[sanking]

Kirk,

Yes, I believe biasing the b to g readings by (2XBlue + 1Green) /3 will give you the closest values to effective printing density with VC papers. But you could expect this value to value slightly according to developer and paper, and probably with filtration. Exactly how much I don't know but you could easily run a check with a transmission step wedge. Expose the step wedge to whatever paper you want to test and give it enough exposure so that you have at least one maximum black step. Then count the steps from maximum black to paper white and multiply by .15. This gives you the exposure scale of the paper (ES) which should match the measured density range (DR) of the negative.

There have been many issues reported with pyro developers and rotary processing, whether Jobo Expert or BTZS. These include uneven staining, development of excessive B+f stain, banding, and virtually everything else you could mention. As a general rule Jobo at normal rpm is too fast for pyro developers and causes excessive general stain, especially with old-style films that have thick emulsions (BPF, TRI-X, HP5+, etc.).

[David_4263]

Hi everyone

I came across this forum while doing some research on the net and found it very strange. I havnt read the full article by this Mr Bond but his conclusion seems very strange. He concludes that their is no difference between the two devolpers. This is strange just for the fact that they are TWO DIFFERENT developers. Each developer is different from another. So maybe he sees no advantage in using pyro, then maybe he should have tested over different formats. Using a pyro based developer on a 120neg will give you very different results to a non pyro dev. The greatest developer i have encounter being Barry Thorntons Dixactol developer. The sharpness and edge effect you can get from this dev is like nothing i had seen before. You can just not get this with a non pyro based dev, as the sharpness and smoother grain is a result of the stain which can be only be got from this type of dev. I can not see how anyone who has used this dev can dissagree. got to go eat lunch with the school kids now will post again soonbye

[David_4263]

Anyway to continue. The reason why prints by people like Ansel Adams and Barry Thornton are in a different league is because of how they expose and then develop their negative. They both use pyro based devs. When i was doing my masters i would be printing next to people who have developed in everything from rodinal to ID11 to various kodak devs. They would all be busy burning in and dodging. They would end up with nice prints but nothing special. Using Dixactol it holds back the highlights in the neg while nursing up the shadows and if you expose your neg reasonably well when making the picture this leaves you with very little burning and dodging needed and of course the excellent sharpness and lack of grain that i have found with no other dev. Other devs can offer fine grain but at the severe lack of sharpness. I find the sharpness of the print the most important aspect. Dixactol gives the greatest sharpness of all devs i have used, this would be at the expense of grain but that is where the stain comes in as it masks the grain. A dev like rodinal which would give sharp prints will leave you with intense grain and no doubt a load of dodging and burning to do. As for the toxic aspect of pyro, i find it a pointless arguement. We are photographers every chemical we use is poisionious dontdrinkthem and dont put your hands in them. Nearly every photographer tones in selinium, this is also highly toxic. I mix various chemicals for toners and alt processes, some of these are cancer causing agents. I mean when photography was first being used most people died early as they were developing in mercery. I am always surprised at the amount of people i see putting their bare hands in the dev stop and fix, then they are surprised when they end up with dermititious and other skin problems. At the end of the day it comes down to care, if you wear gloves as you should always do and dont take to drinking it you will be fine. That goes for pyro and every chemical you use. take care people and forgive my spelling as i am in rush. not much of an excuse i know!!! OH dixactol can also be used as a 2 bath dev. so if you shoot scenes with extreme contrast dev in a 2bath and become amazed as it holds back your highlights and nurses up the shadows. For night work it is amazing. street lights are held back to the point they actually contain detail rather than being a massive white blob that speads across half the image.

dave

[David_4263]

hello again i thought i would add more as i am bored. I thought i would talk about howard bonds thing about unsharp masks, sounds like a bit of a fetish he has going on there. Anyway it seems to me that it is just another technique to cover up a neg that doesnt do the job. A perfect neg should need no burning or dodging and should show detail from highlights to deep shadow. This masking and other things like split grading are all things that are there to cover a neg that doesnt do the job. Here is where my fav dev again comes into play, if you expose properly using the zone system and such, and use a dev like Dixactol then it really isnt that hard to get a perfect neg. Please read the articles on Barrys site, www.barry-thornton.co.uk or buy some of his books. It is so rewarding to print a neg, straight with no messing around to cover up mistakes. The sharpness is amazing which would make the whole masking stuff unnessacery, as it must be such a hassle making a mask for each image. If you have had the pleasure to see Barrys work and realise the ease at which he obtained the results then it is truely encouraging. I have seen lots of images by many technical photographers and barrys surpasses them all, even Ansel. You see 35mm prints that he has made WOW. I sometimes think that people like Bond like the mysticism that surounds their technique, it gives them the status of master photographer. People like Barry Thornton take the opposite route by showing you how easy and available to all these excellent results are.

Barry has made numerous devs, one very nice one is for kodak tech pan film, when used for pictorial work, tech pan is sharp and fine grain anyway, the problem is always contrast control. Barrys dev for this does the job very nicely and you end up with 120 images that look like 5x4 images.

Another nice thing about dixactol is that the stain is brown. pyros stain is usually green which softens the contrast on VC paper. the brown stain cannt be read by VC paper so this helps with gaining the correct contrast during printing. while pyro has a very obvious stain most of it isnt effective stain, a dixactol neg has a far greater effective stain. Which of course adds to grain control.

later

[steve_4345]

I think I read through most of the Pyro correspondence and I can't remember seeing any reference to Gordon Hutchins book on the subject. He addresses the issues of safety in very reasoned way. As another respondent pointed out, all photo chemicals are toxic and the use of masks and glove are to be recommended. If you are committed to wet work this is an issue you have to deal with. In my experience, despite the health concerns, photographers seem to live long and active lives (OK, Weston used Pyro and had Parkinson's........could have been the Amidol though). As for what Pyro brings to the party, just the most luscious negative with the most beautiful separation of detail (especially in the 1/4 tone and highlight regions). Just look at Weston's work and even commercial work from the 30's and 40's. The lack of grain and smooth gradations are just fabulous. If you want your work to have that tonal volume then PMK pyro is the way to go.

[Jorge Gasteazoro]

Welcome back Dan! good to see you posting again. Tell us how the trip went.