Article on Pyro Developers

[sanking]

I have a new article on Pyro developers now up at http://unblinkingeye.com/Articles/PCat/pcat.html

Welcome any comments, corrections, suggestions, etc.

 

[David A. Goldfarb]

Very informative and detailed article. The only additional thing that might be interesting, if it could be done successfully for presentation on the web, would be some illustrations from negatives and/or prints showing the effects of different pyro formulas, maybe with a standard developer or two like D-76 or HC-110 in there for comparison. I realize that there are resources like this out there in back issues of _View Camera_ and such, but it seems like this would fit naturally here.

 

[Francesco]

Well done Sandy. Just printing out a hard copy right now. I have a question concerning two points:

1. In this article you recommed a presoak in distilled water of 5 min. in BTZS tubes. In another you recommended 2 to 3 mins. Any real difference? (BTW, I place the distilled water in the tube caps and then shake it well for about 2 or 3 mins).

2. You recommed the use of a stop bath in the article. How long time should the film stay in the bath? You have also stated elsewhere that 1 minute in water was good enough if the fixer used is TF-4. Is this still the case? (By the way, I put the stop bath in extra BTZS tube caps and agitate slightly for about 30 seconds before I let the film lie in plain water for 1 minute. What do you think?).

Once again, congratulations on a well-written and generously-given article.

 

[Alex Hawley]

Thanks Sandy for this excellent article. Comprehensive and well-written. The best overall reference I've seen concerning all of the pyro developers. I'm adding it my reference notebook..

 

[Ole]

I'll just add my praise and appreciation to those above.

Thanks a lot!

 

[sanking]

The only additional thing that might be interesting, if it could be done successfully for presentation on the web, would be some illustrations from negatives and/or prints showing the effects of different pyro formulas, maybe with a standard developer or two like D-76 or HC-110 in there for comparison. I realize that there are resources like this out there in back issues of _View Camera_ and such, but it seems like this would fit naturally here.

David,

Actually, I am not sure that there are any comparison illustrations of this type in back issues of View Camera. I have not seen them.

However, showing these differences is definitely something that I have thought about doing. Any ideas about the methodology for doing this in an effective way for showing on the web?

Sandy

 

[sanking]

Well done Sandy.

1. In this article you recommed a presoak in distilled water of 5 min. in BTZS tubes. In another you recommended 2 to 3 mins. Any real difference? (BTW, I place the distilled water in the tube caps and then shake it well for about 2 or 3 mins).

2. You recommed the use of a stop bath in the article. How long time should the film stay in the bath? You have also stated elsewhere that 1 minute in water was good enough if the fixer used is TF-4. Is this still the case? (By the way, I put the stop bath in extra BTZS tube caps and agitate slightly for about 30 seconds before I let the film lie in plain water for 1 minute. What do you think?).

Francesco,

I use a five minute pre-soak time because it adds to consistency of results when testing various films, especialy with short development times. Rate of develoment depends on induction and transfer of chemicals into and out of the gelatin emulsion, and the rate varies among films. At five minutes they all perform about the same. For any given film a 2-3 minutes pre-soak should be fine.

About the stop bath, when using a diluted acetic acid bath the film only needs to stay in the bath for 10-15 seconds. If using water, change the water 4-5 times over a period of about a minute.

 

[Donald Miller]

Sandy, Thanks for your efforts in behalf of the photographic community. This article is both comprehensive and concise.

 

[doughowk]

Great article. Hope to see this level of quality for articles in future APUG mag. I'll be trying Pyro HD this weekend for negs to be printed on Azo, and will use this info as a guide.

 

[jbrodkey]

Terrific article. I printed it out and would like to try Pyrocat instead of the Rollo Pyro which I now use. However Sandy says you should mix the stock solutions under a hood or outside.
I live in an apartment house - no hood and hard to work outside. Photographer's Formulary
only supplies the powder although they do provide the stock solutions for several other Pyro developers. Why don't they supply Pyrocat in liquid form. Is there some reason for only supplying the powder?

 

[sanking]

However Sandy says you should mix the stock solutions under a hood or outside.
I live in an apartment house - no hood and hard to work outside. Photographer's Formulary
only supplies the powder although they do provide the stock solutions for several other Pyro developers. Why don't they supply Pyrocat in liquid form. Is there some reason for only supplying the powder?

First, thank you for your nice comments about the article.

I can't speak to Formulary's marketing practices since I have no involvement with their distribution of Pyrocat-HD.

As to the other issue, the recommendation to mix the chemicals outside or with a vent hood is made to err on the side of safety. I personally mix indoors with a filtered mask of the type available at hardware store, taking care to keep the chemicals being mixed downwind of any air currents that may be present, and would not hesitate to recommend this procedure for any reasonably prudent and careful person.

 

[john_s]

What a great article. It's time for me to mix some up and try it. One part of the mixing instructions I was not sure of, mixing part B. When you say that the "The total amount of solution will be slightly in excess of 1300ml" does that mean that the instructions for part B actually make 1300mL?

In other words, if I want to make 1000mL of part B should I use 769g of potassium carbonate?

Most formulas end with "water to make 1000mL"

I've avoided trying Pyrocat-HD because I thought it might be a little grainy for my small negatives, but I'll give it a try.

 

[Ole]

I mix mine indoors, in the darkroom. No hood or anything, either.

The two most dangerous ingredients are the Pyrocatechin itself, and the Potassium Carbonate.

The basic safety precaution is to keep fingers and nose well clear of chemicals; weigh carefully; and mix quickly.

Avoid blowing (includes sighing, sneezing and even gentle exhalation) into dry chemicals to avoid spreading them about. In the same way, don't inhale them. If you can smell the Pyrocatechin, you're a little close. A mask is a good idea, but it may lure you into getting too close.

I would not mix chemicals outdoors if there's even the slightest chance of a breath of wind for the same reasons: I like dry powder to stay put.

 

[sanking]

What a great article. It's time for me to mix some up and try it. One part of the mixing instructions I was not sure of, mixing part B. When you say that the "The total amount of solution will be slightly in excess of 1300ml" does that mean that the instructions for part B actually make 1300mL?

In other words, if I want to make 1000mL of part B should I use 769g of potassium carbonate?

Most formulas end with "water to make 1000mL"

Thank you for alerting me to this matter.

This part of the article is confusing and will I will see that it is changed as soon as possible. With the Stock Solution of Pyrocat-HD we should start with 1000ml of water and slowly add to the water 1000g of potassium carbonate. This will make a total amount of Stock B solution of approximately 1300ml. Previously published formulas made this step clearer but I can see that there could be some confusion with the directions as provided in the article.

 

[Ole]

Sandy,

Think you could change the recipe to give 1000ml final solution? It would be a lot easier for those of us who put the finished solutions in 1000ml (or 100ml, in my case) bottles.

Since I have a very good little electronic balance, I make 100ml at a time. A whole liter would give 100 liter finished developer at 1:1:100, which would be more than I can use. 100ml is generally used in a couple of months; well within the lifetime of the solutions. My first batch lasted me six months, with no sign of deterioration. BTW, I use Nalgene bottles...

 

[john_s]

Ole says above"Think you could change the recipe to give 1000ml final solution? It would be a lot easier for those of us who put the finished solutions in 1000ml (or 100ml, in my case) bottles. "

That's what I was driving at when I suggested 769g with water to make 1000mL, based on Sandy's figure of 1kg pot carbonate plus 1Litre water to make "approximately" 1.3Liter. If it's hard to get all of the pot carbonate to dissolve (sounds like a possibility) i'd be tempted to make up half strength part B and use 2x as much (as I do with PMK, since I found it impossible to get the full amount of metaborate to dissolve in the required amount of water)

 

[Black Dog]

vvg article-excellent intro but covers plenty of ground as well. You mention using hypo clear btw-won't the sulfite in this remove some of the stain?

 

[clay]

I can address the enlargability issue. I use pyrocat with 35mm film, and the grain is about the same as the tried and true d-76 1:1. It is noticeably sharper because it doesn't have all the sulfite that D-76 has in it. I find it to be a perfect roll film all purpose do-anything developer, without the fussiness of the other pyro formulations.

Clay

 

[Donald Miller]

Jdef,
I can address several of your questions based upon my personal experience with both developers. I have used ABC before I switched to Pyrocat. The matter of staining and VC paper is not so much a matter of stain as it is the color of the stain.

In pyrocat the brown stain color does not have the effect of reducing high print value contrast to the extent that ABC does (due to the brown versus greenish stain). Green is the light color that gives a reduction in contrast with VC papers whereas blue serves to increase contrast. I noticed a marked difference with the first Pyrocat developed negatives that I enlarged on VC paper. Additionally I have found that Pyrocat does not suffer from the uneven development that I experience with some of my ABC negatives.

I have found that in several films that there is an increase in effective film speed. Bergger BPF 200 for instance benefits by 1/3 stop over ABC.

I would concur with Clay that Pyrocat is a good developer for a variety of applications. The only area where ABC may have a slight advantage to Pyrocat is possibly in shadow tonal separation. I believe that Sandy King addressed that on the Azo Forum sometime ago. Pyrocat does offer better highlight tonal separation then ABC however.

 

[Donald Miller]

Jdef,
No the benefit of a staining developer is that it is proportional to silver density so that the stain effect is greatest in the areas of greatest silver density. Therefore a staining developer will serve not only to increase overall negative contrast but also to increase local contrast in the areas of higher negative density (print highlight areas).

In the case of a staining developer that imparts a greenish stain (ABC and PMK) with VC materials the effects are counter to the desired result. We are increasing contrast with the stain effect but then we are decreasing contrast through the color of the stain. This occurs by the fact that the stain color acts as a variable contrast filtration factor in it's own right.

To decrease print highlight contrast would tend to lump the highlight values into a blocked condition at it's extreme condition. To increase highlight contrast is to separate highlight values into more definable values. I hope that I have expressed this clearly.

 

[clay]

I think the specific question you had was about VC paper and highlight control.

There are two things going on - the first is tanning of the gelatin. This is common to all the pyro type developers, including pyrocat. The tanning action hardens the gelatin and helps prevent runaway, or infectious development in really hot highlight areas. This is one way that all pyro type developers are supposed to help 'tame' really bright highlights. Think of this contrast control as a 'global' effect that will affect the entire density range of the negative

The second issue is the stain color. This is where pyrocat differs from PMK, ABC and Rollo. All except ABC use metaborate to create the high pH necessary to develop the film, and it will cause a yellow-green stain. In fact, I have proven accidentally that if you use metaborate and part A of pyrocat together, you will get a green stain, not to mention a bulletproof negative! This green stain ideally is proportional to the silver density, so the highlights are more green than the shadows. The green effectively filters the bluish high contrast light that affects the high contrast part of VC paper emulsion. So a green pyro proportionally stained negative will cause the highlights to print softer 'automagically' on VC paper. Think of this contrast control as 'local', since its effect is concentrated where the most stain occurs, i.e. the highlights.

Pyrocat, on the other hand, has a brown stain color, and does not seem to cause the same highlight softening as the metaborate based developers and ABC. So, you get more highlight contrast with VC papers and pyrocat. But you still get the global highlight control of a tanning developer. So the statements are not necessarily contradictory, as I think Sandy is referring to two different attributes of the developers.

Of course, I'm putting words in Sandy's mouth, so Sandy, call me down if I am full of it.

Clay

 

[sanking]

"Hi Sandy. I've found one point a little confusing. In your introduction, under advantages of pyro developers in point #3 you state " 3. When printing with variable contrast papers, pyro stain, which is always proportional to silver density, functions as a continuous variable color mask that reduces printing contrast, particularly in the high values. This allows shadow and mid-tones to be printed without compressing or blocking the highlights, reducing time spent burning and dodging. ", which suggests to me that reducing contrast in the high values is a good thing. Later, under Is Pyrocat Better Than Other Developers, you state "9. When printing with silver gelatin variable contrast papers Pyrocat-HD renders upper middle tones and highlights with more contrast than pyrogallol-based developers. ", which suggests that a reduction in contrast in the high values is a bad thing."

The fact that pyrogallol based developers reduce contrast in the highlights and that Pyrocat-HD renders these highlights with more contrast is neither a good thing nor a bad thing -- these are characteristics of the developers. Some subjects would benefit from the highlight compression, others would not.

"I've read reports by others that Pyrocat gives LESS speed than ABC, but you claim it gives more. Since you're the obvious authority in the use of this developer, I'm inclined to take your word, I just want to be sure that I'm understanding the information correctly."

I know for a fact that Pyrocat-HD gives more effective film speed that ABC Pyro. For that matter both PMK and Rollo Pyro do as well. I saw one report on the AZO formum by someone who said that he got more speed with ABC Pyro. But it was obvious from his description of results that the comparison tests were not develoed to the same CI, and it is pointless to compare effective film speed from different developers unless the films are developed to the same CI. Also, very few people have the equipment to really test effective film speed accurately. My exposures are made with a light integrator that guarantees accuracy to 1/100 of a second, and any comparsion development that I do has careful temperature control.


"You say that Pyrocat is an excellent choice for dual purpose negatives, silver and alt., but if I'm understanding your information, it is really an excellent choice for any purpose, i.e contact/enlarging small format/large format, tray/rotary etc. Is there any scenario in which another developer would be a better choice?"

OK, in what conditions would another developer give better results?

1. For 35mm work with some films you might want a tighter grain patterns than you get with Pyrocat-HD.

2. For scenes with a lot of very high tonal values the compression you get with PMK or Rollo Pyro might work better.

3. If you are after strange curves there are developers out there that will give interesting non-linear curves, unlike the nice linear, straight curves you get with Pyrocat-HD.

4. I would not use Pyrocat-HD for developing color emulsions.

Sandy

 

[andrewfrith]

im looking for a source for the Potassium Carbonate mentioned in Sandy's formula..i cant see it on the list at artcraftchemicals but can see potassium bi-carbonate (anhydrous) at photographers formulary..is the bi-carbonate the same stuff in sandy's formula?

-andrew

 

[PaulH]

Potassium Carbonate is not in order with the rest of the Potassium compounds on Artcraft's site. Just keep scrolling down or search the page for it. It is near the bottom of the chemical compounds just before the Zonal Pro chemistry.

 

[Michael A. Smith]

I've posted this elsewhere, but felt I should do it here.

Sandy's article is one of the best articles about the technical aspects of photography that I have ever read. For those interested in developing negatives with Pyro this is a must read.