During the course of the past year or so, I received several phone calls from people who are attempting to use a pyro based developer. Usually, the formula they are using is Gordon Hutchings PMK formula. They have questions about it use, or relate some problems they encounter with it. I will write about some of the more common problems seen, and some tips to help solve those problems.
The most common problem I am asked about deals with the staining process that is a characteristic of this developer. The issue concerns a lack of staining, or what the individual perceives as weak staining. If the person using the developer has never seen a stained negative for a basis of comparison, they do not fully understand what they should be looking for as far as stain appearance and intensity. With PMK, the stain should have a yellow-green color, which can vary in intensity depending upon the film that is used. The beginning root toward maximum PMK staining is that much of it is film choice related. PMK produces the maximum correct stain with "old fashion" emulsions. This includes films such as Kodak Verichrome Pan, Kodak Plus-X Pan, Kodak Tri-X Pan, Kodak High Speed Infrared, Ilford FP4+, Ilford HP5+, and Fuji Neopan 400 and 1600. Films which show staining ranging from moderate to little staining include slow emulsions such as Ilford Pan F+, Agfa APX 25, and the so called "high tech" emulsions which includes the Kodak T-Max films, and the Ilford Delta Films. There are ways to force these stain resistant emulsions to show a higher stain level, which we shall deal with later in this article.
At a very basic level, before anything else is tried, you can use film choice as a way to maximize the stain produced by PMK. Since the developer shows more stain with increasing density levels (more silver halide is reduced), it only makes sense that the older type of emulsions present a greater surface area of reducible silver, which leads to greater staining. The high tech emulsions, and the slow speed traditional emulsions are fine grained emulsions, with a lower surface area of reducible silver halide. Usually, when switching to a higher grained film, the stain will hide a lot of the additional grain when you make the prints, so the tradeoff to get a greater staining will not be a big deal.
The next problem encountered is you are using a film that should be showing a nice stain, but you are not getting that stain. In this instance, it usually indicates an incorrect processing procedure. There are two things that are an anathema to a good stain density when dealing with a pyro based developer; acids, and sulfites. The excess acid is most commonly found in two places: 1. the user forgets to use a non hardening fixer as prescribed by Gordon Hutchings or, 2. the person uses an overly strong stop bath, or a stop bath made up of a chemical inappropriate for use with a pyro developer. The first instance is easy to correct. Use a non hardening fixer such as the Kodak Fixer 24 formula, or mix a rapid type fixer 1+3 and do not add hardener to the solution. The latter method is the one I prefer. What happens is the hardener contains an excess of acid, which in the case of rapid type fixer hardener, is sulfuric acid. This will wash away a lot of the stain the film has developed in the course of processing.
In the case of the stop bath, it has been mixed too strong, or a citric acid stop bath has been employed. Gordon Hutchings recommends using acetic acid at 1/3 its usual strength, and then discarding the solution after use. If you use, for example, a stop bath made up by adding 45 ml of 28% acetic acid to 1 liter of water, use 15 ml of 28% acetic acid instead. Citric Acid is very useful as a stop bath, since it produces less odor and can be mixed at the time of usage from the powdered chemical due to its high solubility. However, citric acid has a property that is favorable in most instances, but unfavorable for use in tandem with a pyro developer. Citric Acid is a clarifier and stain remover, which is exactly what you do NOT want to be doing when using a pyro based developer. You may eliminate the stop bath concerns altogether by using a plain water rinse between the developer and the fixer. The slight extra development accorded the film by this method should have no practical effect, owing to the development latitude of this developer. Sulfites come into play when a wash aid is used following the post fix staining bath (which you have not forgotten to use after the fix, have you?). Not only are wash aids not needed before the wash, but they will remove much of the stain you have worked so hard to achieve. If I can be anthropomorphic for a moment, the sulfites in the wash aid "see" the stain as a form of oxidation, so it "stops" the oxidation and thereby removes much of it. It is doing its job, but it is doing it where you do NOT want it to be doing it.
The alkaline stain bath following the fixer (either the used developer, or a separate bath made up of an alkaline) also acts as a wash aid without resorting to sulfites, because the alkaline reopens the emulsion, and allows the fixer to be carried away easily in the wash. Which brings up another point; most of the heavy staining occurs in the wash itself, so be sure to allow for about twice as much washing as you would for films developed in non staining formulas. For example if you use five fill and dumps for film developed in a non staining developer finished in a wash aid, use 10 fill and dumps for a PMK developed film, or ten minutes of wash instead of five minutes of wash. Whatever your normal wash procedure is, double it.
OK, you have tried these basic steps to improve the staining performance of the developer, but you want to go further, Either you still want to use a film that does not normally show much stain in PMK, or you want to REALLY stain the film for whatever reason. We now make a couple of modifications for you adventurous types. The first way this can be accomplished is to use a post fix stain bath that is stronger than the two recommended ones (used developer, or sodium metaborate in water). This is easily accomplished by using a sodium carbonate post fixer stain bath. This can be done by adding a teaspoon or two (amount not hyper critical) of sodium carbonate in a liter of water. The type of sodium carbonate used is not critical either. You can use normal monohydrated sodium carbonate sold by photochemical suppliers, Arm and Hammer Washing Soda (decahydrated form) or HTH Pool pH Adjuster (anhydrous form). In any case, what we are doing is using a stain forming bath that is 10 times stronger (approximately) than the normally used developer, sodium metaborate stain forming bath. The stain will be stronger, but so will the non image stain seen in older pyro formulas. The negative will take on some brownish color along with the normal yellow-green color.
If you want to be really radical with this idea, you can mix up the PMK B bath with sodium carbonate instead of sodium metaborate. This procedure alas, defeats many of the purposes of the normal PMK formula, which was to give maximum image stain with minimal general stain, and a working solution with a longer useful life. The sodium carbonate will cause the working developer to oxidize much more quickly, and cut its useful life by about ½. If you use development times in the neighborhood of 8-12 minutes at 70°F, this is not really much of a problem. If you want to use the developer for 20 minutes for a maximum N+ development, then forget it, the developer will not "live" that long using carbonate. This procedure will produce an extreme stain with older emulsions, and a more obvious stain with the high tech or slow speed emulsion. To do this, mix the PMK B bath as follows:
| Chemical | Amount | Units |
|---|---|---|
| Distilled Water (75°F) | 600 | ml |
| Sodium carbonate (mono) | 180 | g |
| Water to make | 1000 | ml |
To use, mix the developer in the normal way (1+2+100). The post fix stain bath in this instance is the used developer, so the film gets a double dose of carbonate. You will see a brownish color that may obscure the yellow green stain. This is general stain caused by the higher oxidation rate of pyro when in a solution containing sodium carbonate. As I stated before, this is not the intention of the original PMK formula, but some people like the effect. You may even pick up about ½ stop of additional film speed due to the higher activity of the metol in the carbonate boosted solution. As always, run tests before committing important film to this modified developer. Again, I reiterate, this procedure should be the LAST one attempted if you are having low staining problems. The earlier recommendations in the first paragraphs of this article should be sufficient in a majority of problem cases. Keep your ventilator filters clean, your latex gloves handy, and good luck!
REFERENCE
PMK Film Developer Kit No. 01-5050,
Photographers' Formulary (800-922-5255).
The Book of Pyro, Gordon Hutchings