Unblinking Eye
                                 Pyrocat-HD Film Developer


Pyrocat-HD is a semi-compensating, high-definition developer,  formulated by Sandy King as an alternative to PMK. The advantages over PMK that Mr. King cites for his formula include an approximately 1/3-stop greater effective film speed, 10-15% shorter development times, more consistent staining action, lower toxicity, and no streaking or mottling with reduced agitation.  Other users have reported reduced printing times with UV light sources compared with PMK negatives (for alt process work) due to the different stain color, as well as reduced base plus fog density compared with PMK and Rollo Pyro negatives in rotary processors.


Stock Solution A

Distilled Water

   750 ml

Sodium Metabisulfite

   10  g


   50 g


     2 g*

Potassium Bromide

   1  g

Distilled water to make

   1000  ml

Stock Solution B

Distilled Water

   700 ml

Potassium Carbonate

  750  g

Distilled water to make

1000 ml

To make a standard working solution mix 1 part A with 1 part B
with 100 parts water.

* Or substitute 25 grams of metol (with a slight loss in film speed).

Note:  The formula provided here differs from the one published in Post-Factory Photography, issue number 4.  Mr. King has modified solution B to use a 100% solution of potassium carbonate instead of a 10% solution of sodium carbonate, and 1 gram potassium bromide instead of 2. An earlier version of the formula published on the rec.photo newsgroup called for 2.5 grams of metol in place of the phenidone.  Mr. King suggests that this formulation may be more stable than the phenidone version. The keeping time for solution A when formulated with phenidone is about 3-6 months.  Ted Kaufman has recommended substituting a 10% solution of sodium hydroxide for solution B.

Sandy King’s experiments have centered on sheet film, as he works primarily in large format (4x5, 5x7, 7x17, and 12x20).  His development recommendations are as follows:

Sheet film in trays, normal agitation: standard working solution, with agitation for 10 seconds every minute (or 5 seconds twice per minute), 70º F.

Sheet film in trays, minimal agitation: standard working solution, with agitation for 10 seconds every three minutes, 70º F.  Development times are approximately 50% longer than for normal agitation.

Sheet film in trays, semi-stand agitation: special working solution of 1 part A with 1 part B with 200-400 parts water. Agitation is for one minute at start of development, followed by 30 seconds at the half-way point.  Development time for slow and medium-speed films is 40-50 minutes, 70º F.  Development time for fast films is 50-60 minutes.  Dichroic fog may result from extended development of high speed films. If this is a problem in your work use a 1:1: 200 dilution and reduce development to about 30 minutes.

Sheet film in rotary processor, continuous agitation: use a minimum of 75 ml of the standard working solution per sheet of 4x5 film (or equivalent for larger formats).

Recommended developing times for sheet film in rotary processor are as follows: FP4+ (EI 100) for 8 minutes, BPF-200 (EI 100) for 9 minutes, T-MAX 400 (EI 320)  for 12 minutes, and HP5+ (EI 320) for 13 minutes, all at 70º F.

Presoak film for two minutes.  Use a plain water stop bath for one minute. Use an alkaline fixer (rapid fix without hardener) for 5 minutes. Wash in running water 10-15 minutes.

The working solution can be made quite a bit more energetic (faster working) by doubling the amount of B solution. For example, with a 1:1:100 dilution, Ilford FP4+ develops to a CI of .52 in 8 minutes.  With a 1:2:100 dilution, development time to the same CI is only 5:30.  This fact makes the 1:2:100 dilution very useful for zonal expansion, especially for negatives intended for use with alternative processes.

Test Results with 120 Roll Film
by Ed Buffaloe

I’m not running a scientific test here.  I shoot, develop, print and see if the results were worth the trouble.  Thus far, I have been very satisfied with Pyrocat-HD.  Since I don’t have a densitometer, I can’t measure densities to see if I am really getting a one-third stop speed increase. My Pyrocat negatives are beautiful-- very clean, sharp, high-acutance images. I am taking advantage of Pyrocat’s even development to reduce agitation to once per minute for 10 seconds (whereas for PMK I use twice per minute for 5 seconds each). When I wrote to Sandy King to tell him of my preliminary results, he responded as follows:

    My original tests indicated that Pyrocat-HD with the 1:1:100 dilution required slightly shorter development times than PMK, but those tests were all done with sheet film and constant agitation in tubes (floating them in a water bath). However, Pyrocat is a much more energetic developer if diluted 1:2:100 and I use this dilution for all of my development of 7x17 and 12x20 film which are intended for printing with the carbon process. The 1:2:100 dilution also works well for zonal expansion of about 2 steps, keeping time and temperature the same.

My first test with 8x10 sheet film photographs (click here to see the results) indicated that the developing times for PMK and Pyrocat-HD would be very similar.  I think you could go to my chart of developing times for PMK and use them for Pyrocat-HD as a starting point. That is exactly what I have been doing.  However, Sandy King recommends reducing PMK times about 20%. What follows is a chart of films I have tested so far and the times I recommend. The bolded times are the ones I actually used.






Ilford HP-5+


13 min

10 min

8 min

Kodak T-Max 100


14 min

11 min

9 min

Kodak T-Max 400


15 min

12 min

10 min

Kodak Verichrome Pan


9 min

7.5 min

6 min

All the above times are for the 1:1:100 dilution.

One difference between PMK and Pyrocat-HD is the color of the stain. PMK’s stain has a strong yellow-green color, which inhibits blue and magenta. When printing on graded paper, the yellow-green stain adds effective density to the negative and boosts contrast.  When printing on variable contrast paper, the James R. Buffaloe - Click to enlargePMK stain tends to reduce contrast, particularly in the high values. Pyrocat-HD’s stain is brown in color.  Pyrocat negatives print much like PMK negatives on VC papers, but require less exposure on graded papers than similar PMK negatives, because the brown stain doesn’t inhibit the blue light that paper is sensitive to as much as a yellow stain would.  Sandy King has stated that alternative process printers who print with UV light sources find their exposure times reduced with Pyrocat-HD when compared with print times from pyro negatives.

Here is a photograph from a T-Max 100 negative developed in Pyrocat-HD.  The subject is my father when he grew his beard out.  It was taken in open shade on a sunny day with a #22 yellow filter. The print was made on Ilford Multigrade FB with no filtration, and demonstrates a very long tonal scale with good detail throughout.

Semi-Stand Development

I had a roll of Delta 3200 from my vacation that I was certain I had underexposed. I wanted to try to salvage it, so I used Pyrocat-HD with semi-stand development.  I gave it 30 minutes development in Pyrocat-HD diluted 1:1:200 at 70º F.  I agitated for one minute at the beginning and 30 seconds in the middle of development. Not only is the roll printable, it has extremely high acutance--the prints from it appear almost unreally sharp.  (Later, I developed another roll using semi-stand development, only this roll was of a very high-contrast scene, and I thought I could reduce contrast using this development method.  But the bromides released by the intense development in the heavily-exposed areas diffused out and caused uneven development in surrounding areas.  The roll was ruined and I lost some great shots.  It seems that with subjects like this at least some intermittent agitation is required. Additionally, the solutions were old.)


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More on Semi-Stand Development by Michael Emanuel

I have been experimenting with pyrocat HD andI believe I have found a method with Delta 100 35 mm. that is quite amazing in terms of results: incredible acuity, smoothness of tonality, finer grain then with any
other pyro developers, excellent shadow separation, full film speed (IE 100 ).

This technique is as follows: 2 ml pyrocat A, 2 ml. pyrocat B, 500 ml. distilled water at 20 C.  Initial agitation for 30 seconds followed by 2 inversions every 10 minutes for a total time of 45 minutes. Ed buffaloe mentioned the amazing sharpness he attained with 120 film and a modified stand development.  He also mentioned the problem he had with bromine drag. With the method I use I can see no evidence of bromine drag. Also the emulsions seem to have no imperfections.  Needless to say it also very economical.

Test Results with a Jobo Rotary Processor
by Clay Harmon

Pyrocat-HD has become my main developer for making the long exposure scale negatives that the platinum/palladium process requires. It is cheap, easy to mix and robust in its ability to produce an effective actinic (UV blocking) stain with no loss of film speed. I use a Jobo processor for all of my negatives and did run into a few minor problems that I thought would be useful to address.

The minor problems all essentially boil down to minor uneven staining that can occur with the Jobo, due apparently to a sort of ‘bromide drag’ phenomenon. When I used the expert drums for my 8x10 and 5x7 negatives, I noticed an area of lower density on the edge of the film closest to the top of the drum. The uneven staining was consistent, since it occurred on the long axis of the 5x7 negatives and the short axis of the 8x10 negatives.  The effect in my prints looked like a dark streak that went from the midpoint of the affected side of the negative diagonally toward the middle.  It resembled a filmholder light leak in reverse.  The problem was cured by making absolutely certain that the negatives are pushed all the way to the bottom of the drum, and that the bend in the film is toward the middle of the drum when loading.

A related problem was observed when using the Jobo print drums to develop my 7x17 negatives. In the higher density areas of my negatives--sky and fog for instance--I was getting ‘hot’ streaks that were parallel to the short axis of the film, i.e. parallel to the direction of drum rotation.  I found it essential to heed Sandy’s advice to take the drum off of the Jobo every 1-1/2 to 2 minutes and tilt it back and forth while rotating it by hand for about 15 seconds. This is certainly a pain to do, but still beats tray processing in my opinion. These mechanical procedures should also address the same problems if they are observed when using other staining developers such as Rollo Pyro.  I encourage others to try this wonderful developer, if a long scale negative is needed for UV light-based printing processes.

See also Testing Pyrocat-HD, by Clay Harmon.

A Report from Pete Watkins

Ed, it was the information on your web site that encouraged me to try Pyrocat in the first place--thanks.

The two films that were excellent were Kodak T-Max 400 roll film at El 320, developed for 15 mins, and  Bergger BFP 400 sheet film at El 200, developed for 11 minutes, both in the 1 part A, 1 part B, 100 parts water solution. Kodak T-Max 400 roll film at 200, developed for 15 minutes, was a little dense but printable, as was Kodak Tri-X 400 roll film at El 260. Kodak T-Max 100 roll film, developed for 12 minutes at 100 was very thin and virtually unprintable.  If I ever bother again I will expose at 64 and try 13 minutes. I am pleased with the level of staining. I have tried Barry Thornton's Di-Xactol and I feel that the Pyrocat results are better. I am not criticising Di-Xactol, as I changed a lot of other things when I used Pyrocat and any comparison would be unfair.

  • I did everything at 70 degrees Farenheit.
  • I used deionised water for the first washes, for the developer and for the final rinse.
  • I did two 1 minute pre washes.
  • I used Pyrocat-HD in the 1 part A, 1 part B, 100 parts water formula, carrying out torus agitation for the first 10 seconds then for 10 seconds every minute.
  • I used a water stop bath, four 15 second washes (or as near to that as I could get with a 4x5 sheet film tank).
  • I then used TF-3 fixer (stock solution diluted 1-4) for 5  minutes, agitating for the first 10 seconds then for 5 seconds every  minute.
  • I washed the film for 30 minutes and carried out a final rinse with deionised water with a few drops of wetting agent added. 
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