Pyro Developers : LUSENET : Large format photography : One Thread

I am looking for an introduction to Pyro developers what there positves and negatives 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,


-- Matthew Hoag (, February 05, 2001


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

If you are interested in pyro, Gordon Hutchings 'Book of Pyro' is definitive. For the PMK formula, look at also has pyro based formulae.

Cheers, DJ.

-- N Dhananjay (, February 05, 2001.

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.

-- Charlie Strack (, February 05, 2001.

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

-- paul owen (, February 05, 2001.

Just buy a kit from Photographers Formulary and give it a try; you'll have to make 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.

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

IMHO if you aren't shooting 4x5 or larger and/or printing with alt. methods, pyro 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 should give it a try and see how it does.

-- John Hicks (, February 05, 2001.

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.

-- fw (, February 06, 2001.

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?

-- Ben Calwell (, February 06, 2001.

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.

-- Ken Burns (, February 06, 2001.

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::Don'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.

-- C. W. Dean (, February 06, 2001.

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.

-- Charlie Strack (, February 06, 2001.

I've just started using pyro and for me it's still an open question as to whether it's worth the trouble and health risks. If you're just experimenting, I wouldn't buy the Hutchings book right away. I did buy the book and it's excellent but the instructions that come with the Photographer's Formulary kit duplicate the basics contained in Hutchings' book, so if you're not committed to pyro you can save the $30 initially, then if you find that you like it buy the book for the other information it contains. Mixing the dry kit seemed o.k. - I just went outdoors as Hutchings and the Formulary instructions require. I didn't buy the Formulary pre-mixed kit because the quantity of it seemed huge - 25 liters or something like that though now that I've mixed the dry I realize that possibly the lady on the phone was saying it would make 25 liters of working solution, not that it was 25 liters itself. I've been developing in trays with gloves and it's worked o.k. - at least I'm still alive - but I'm very concerned about the possibility of pin hole leaks in the gloves. For that reason I've decided to make some 8x10 tubes per the instructions in Phil Davis' book "Beyond the Zone System" and dispense with the trays. The tubes should pretty well eliminate the health risks once the pyro is mixed. My understanding is that it's possible to use pyro with tubes if you presoak the negatives. To tell you the truth, I haven't noticed any astounding differences in my negatives and prints compared with the D 76 1-1 I previously used. The one batch of prints I've made so far appeared very sharp, but I haven't yet run any serious comparison tests. Also, I haven't really photographed any high contrast scenes yet, which is the situation that intrigues me with pyro. If you know how to develop in trays, I'd say give it a try since the cost is minimal and it will satisfy your curiosity if nothing else.

-- Brian Ellis (, February 07, 2001.

I have been using PMK pyro exclusively for two years now, 4x5 in the combi tank, and 8x10 tray developing with surgical gloves. I am mostl printing alternative processes, but found it also superb or silver bromide.


-- Lukas Werth (, February 10, 2001.

I tried PMK and so far it works OK. Another issue with it is it seems to work best with certain films. With some films the negs don't look too much different from standard developers. TMY seems to give the best response that I have encountered. I bet it works great with Berger. I would say that the greatest benefits are for those who do alternative process where that extra contrast is very helpful.

-- Jeff Tatterson (, February 13, 2001.

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