Pyro Developers

[Matthew Hoag]

I am looking for an introduction to Pyro developers what there positves and nega tives are - just to get off the ground and if they are commercially available or can only be made my mxing your own chemistry.

Many thanks,

MH

[N Dhananjay]

Pyro is an almost mythical developing agent. Early versions of pyro formulae include pyro ABC (named for its three stock solutions). Pyro is said to have several advantages. First, it hardens the emulsion and thus makes for a sharper image by preventing the crystal from spreading. Two, it is said to create adjacency effects with ease. Three, it ads a stain to the film which is proportional to density and this stain is actinic i.e., it acts as printing density. Therefore, a pyro negative needs to be developed for a less dense silver image (therefore, reduced graininess). The stain also acts to fill in the spaces between the grains and thus reduces graininess further.

Early pyro formulae were said to be fickle - created staining and streaking etc, not to mention the fact that it is probably one of the most toxic compounds in the darkroom. Yet it was the developer of choice for Edward Westoin. A recent pyro formula that is said to have cleared up many of the problems with pyro is Gordon Hutchings PMK (for pyro metol kodalk). It is available in premixed form from www.photoformulary.com.

If you are interested in pyro, Gordon Hutchings 'Book of Pyro' is definitive. For the PMK formula, look at http://www.jetcity.com/~mrjones/pmk.htm. http://www.unblinkingeye.com/Articles/Developers/Formulas/formulas.htm also has pyro based formulae.

Cheers, DJ.

[Charlie Stracl]

PMK is available from Photographer's Formulary as 2 separate solutions you mix before use.

Reported Positives: great mid-tone and highlight separation handling difficult situations well

Negatives: Pyro is highly toxic. Handle with gloves only. It'll do in your kidneys if you don't treat it with respect. Many formulas are touchy, but PMK seems stable.

[paul owen]

Matthew, I used to swear by PMK, it really is an outstanding developer, but there is an even better alternative. Try DiXactol from Barry Thornton here in the U.K. It is a staining developer that can be used as either one shot or 2 bath and has none of the "NASTY" side effects/toxicity of pyro. It gives the same olive green/yellow stain and is far less prone to streaking through agitation/uneven development.It can be purchased ready prepared in 2 solutions ready for mixing and comes with an excellent set of instructions too!! Regards Paul

[John Hicks]

Just buy a kit from Photographers Formulary and give it a try; you'll have to ma ke up your own mind.

The use of pyro has garnered many aspects of a religion.

I'll go ahead and get my two cents worth in. <g>

Modern staining developers such as PMK Pyro, DiXactol, Rollo Pyro etc have som e useful properties in that highlight contrast can be greatly compressed when pr inting on VC paper, and a neg's CI and D-Max can be enhanced for printing with a lt. methods without the tremendous sharpness-destroying grain penalty of develop ing to make those negs with standard developers.

IMHO if you aren't shooting 4x5 or larger and/or printing with alt. methods, p yro shows pretty much only disadvantages.

But I think everyone would agree that if you're interested in a pyro developer and are prepared to deal with the hazards involved in using it, you really shou ld give it a try and see how it does.

[fw]

It's worth saying that DiXactol (pyrocatechin) is of a similar toxicity to Pyro (pyrogallol), and is absorbed through the skin in the same manner, and hence should be handled with similar care to that for pyro.

[Ben Calwell]

Regarding Pyro; I would love to try it, but I'm not willing to risk my health doing it. For those of you who use it, is wearing rubber gloves enough protection? And what about breathing it? If I splash a little of it and it drys, will Pyro dust circulate through my house?

[Ken Burns]

Matthew: To avoid any confusion that might occur, N Dhanajay's statement above that the stain produced by pyro is actinic is incorrect. The stain is usually yellowish to yellow-greenish. An actinic stain would be at the opposite end of the spectrum, in the bluish area of the visible spectrum. An actinic stain would allow blue and unltrviolet light to pass through the negative. The yellowish stain filters out blue and unltrviolet light.

This is a major issue if the negatives are to be printed on variable contrast papers. Actinic light would cause a higher contrast print to occur than would yellow light. Since yellowish or greenish light reduces contrast with VC papers, pyro can handle extremely contrasty situations. If the pyro stain was actinic, the negative would be suitable if the original scene was low in contrast.

[C.W. Dean]

With regard to questions of safe handling of Pyro. Gordon Hutchins covers the hazards and precautions in great detail in his "Book of Pyro". It mostly comes down to:on't inhale the powder dust when mixing and don't touch the liquid or powder with bare skin. Certainly the powder residue from evaporated solution can be considered hazardous and careful disposal of all exhausted chemistry, a part of sensible lab practice, is important. The safety precautions are not difficult, elaborate, or expensive but those who have any reservations about the real hazards of pyro might feel more comfortable with less toxic chemicals. Read Hutchins for more details--he has done the research and homework.

[Charlie Stracl]

To answer Ben's questions:

1. Gloves are good enough when handling the solution.

2. Don't let pyro or any other photographic solution dry. Clean it up. All the chemicals powders can get in the air and do damage to your lungs.

3. Buy the pyro liquid kit so you don't have to mix the powders.