Being new to this site, I have seen many mentions of Pyro developer in the forum, but all at a pretty high level. Can someone explain to the uninitiated;
- what is Pyro?
- why use it?
- what is the effect on the print?
- what films are best used with pyro?
- how difficult is it to use?
- where can you buy it in the UK?
"Pyro" is just another type of developer for films. For some, it is just mumbo-jumbo. For others, it is staining developer which is used to try to squeeze as much exposure latitude out of a film as possible.
There are several types out there now, with differing characteristics. One which has come into favor is called "Pyrocat HD" and was developed by Sandy King. He wanted a staining developer which would maintain film speed. Another type used pyrogallic acid and is also relatively new, PMK pyro. This was created by Gordon Hutchins to try to avoid some of the pitfalls of older Pyro formulas (uncontrollable staining, strange results and inconsistencies). An advantage to staining developers in general is proportional stain, the ability to create a "fog" around certain portions in the image (typically in the highlights) which helps control contrast.
Since I have not yet used Pyrocat, I'll stick with PMK. There is a print in the "Critique Gallery" posted by Francesco, "1720cc beast," which used PMK for the developer (scroll back a few pages to find it). This print was done in some pretty harsh lighting (full sun in Artizona) and had some very intense specular highlights. The highlights came out well. With PMK there is about 60% of the image from stain, this stain fills in the area around film grain and makes possible the very smooth appearance and lack of apparent grain in the image (using a fine grain film helps also). On the negative side with PMK, film speeds are cut in half and general stain can reduce "micro-contrast," most noticeable in the shadow areas as a murkiness.
The older style films seem to work best in pyro. I use a lot of Efke film, but FP4, Tri-x, HP-5 and a lot of others work as well. Check some other forums to see what is out there.
Pyro developers tend to be of the "one shot" variety. You use it and then throw it away as it will be depleted when working. It is very inexpensive to use and small amounts are required for each batch. Use distilled water for mixing pyro, or times can vary wildly with local water quality.
Don't know about availability in the U.K. but I'm sure someone will be able to help you with the information.
Pyro is indicative of a chemical formulation utilizing either Pyrogallic acid or Cathecol.
Originally Posted by Snapper
The reason to use one of these classes of developers is 1. Increased sharpeness due to adjacency effects. 2. Proportional stain...that is stain is greater in high silver density regions of the negative. This increases hightlight tonal separation. 3. Ability to build higher density range (contrast) in the negative. This is important to photographers who work in alt process or Azo.
While most black and white films will benefit from pyro development, the films that benefit the greatest (due to the ability to expand contrast) from pyro appear to be Tmax 400, FP4+, Efke PL 100.
It isn't difficult to use. There are important safeguards that are encouraged. Those are the use of a respirator when mixing powders and the use of gloves to eliminate hand contact with the liquid developer.
I am not certain about the UK. I buy my chemicals from Artcraft and mix the developer from the individual ingredient chemicals. Artcraft and Photographers Formulary both sell kits in which the appropriate chemicals are already formulated.
In addition to the benzene ring compounds Pyrogallol and Catechol (also called Pyrocatechin and Pyrocatechol) there is Hydroquinone, which is a benzene ring compound that is chemically and functionally very similar to Catechol. Sodium or Potassium Sulfites in sufficient concentration in the developing solution will prevent or retard stain formation and tanning with any of these "Pyro" developing agents.
In my own direct experience, roll and sheet films that work well with staining and tanning (i.e. Pyro) developers include: Ilford Pan F+, Ilford Delta 100 and 400, Ilford HP5, Kodak TMAX 100 and 400, Kodak Tri-X, Fuji Acros, Efke 100 and 400, J&C Classic 200 and 400.
I prefer Sandy King's Pyrocat-HD formulation which I mix myself "from scratch."
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You might also take a look at Sandy King's article
Introduction To Pyro Staining Developers on The Unblinking Eye site.
Originally Posted by Donald Miller
More on Donald's comments re: the reasons for using Pyro.
1. Adjacency effects -- Adjacency effects result from local developer exhaustion and can be obtained with other high definition developers, Rodinal for example. High definition developers are highly dilute solutions that contain about one gram or less of reducer per liter of working solution. Note that not all Pyro developers are high definition developers. PMK with 1.0 g of reducer per liter at the 1:1:100 dilution, and Pyrocat-HD, with 0.5 gram of reducer per liter, are high definition developers. ABC Pyro and Rollo Pyro, which contain from 4.5 g to 6.0 g, are not high definition developers because they will not normally produce adjacency effects.
2. Irradiation minimized -- There is yet another reason why Pyro negatives are sharper, and this applies to all Pyro developers, not just high definition ones. With Pyro developers the gelatin is tanned or hardened in the first minute or so of development, and this restricts most of the development action to at and near the surface of the emulsion. This fact minimizes the effects of irradiation, i.e. the scattering of light deep in the emulsion that results from light reflecting off silver grains.
3. Stain -- The role of stain in a Pyro developer is to mask film grain and boost effective printing contrast. Low-staining Pyro developers, ABC Pyro for example, produce very large grain. Pyrocatechin in non-staining formulas produces smaller grain than Pyrogallol but it too benefits from grain masking in a staining formula. PMK, Pyrocat-HD and Rollo Pyro are all staining formulas. Staining formulas give provide the sharpness inherent in tanning developers with the added benefit of less graininess.
Sandy forgot to mention that the staining developers provide negatives that have much higher contrast for blue and UV sensitive printing materials such as graded silver paper and platinum, palladium and others. The same negative that is high enough in contrast to print on these materials will not be too high to print on VC paper.
To put it in non tech blonde speak, it makes your negatives sharper. I use to use D-76 and had fine images, Now that I use a pyro developer, I have images that are very tack sharp.
IMHO the best of the formulae is still the PMK developed by Gordon Hutchings in the early 1980s. The definitive work is called The Book of Pyro also by Hutchings. I have used this formula for 25 years and have never felt a reason to switch. If someone can prove to me there is a better pyro formula please do so.
The Book of Pyro and the pre-mixed A and B solutions are available from Bostick and Sullivan and The Photographer's Formulary.