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.
STOCK SOLUTION A
| Chemical | Amount | Units |
|---|---|---|
| Distilled Water | 75 | ml |
| Sodium Bisulfite | 1.0 | g |
| Pyrocatechin | 5.0 | g |
| Phenidone | 0.2 | g |
| Potassium Bromide | 0.5 | g |
| Distilled water to make | 100 | ml |
STOCK SOLUTION B
| Chemical | Amount | Units |
|---|---|---|
| Distilled Water | 100 | ml |
| Potassium Carbonate | 100 | g |
MIXING THE STOCK SOLUTION
To make a standard working solution mix 1 part A with 1 part B with 100
parts water.
USAGE
Mr. 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).
Sheet film in trays, minimal agitation:
Standard working solution, with agitation for 10 seconds every three
minutes. 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. 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
HP5+ (EI 320) for 13 minutes.
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 0.52 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.
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. An earlier version of the formula published on the rec.photo newsgroup called for 0.25 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 6 months.
Ed Buffaloe Test Results:
Developer:
Pyrocat-HD formulated with 0.25 g of metol
instead of phenidone in stock solution A,
and utilizing a 100% solution of potassium carbonate
for stock solution B. I used Mr. King's standard 1:1:100 dilution.
Film
120 Format TMX 100
Test Developing time: 10 minutes.
Temperature: 70°F.
Technique
2 minute presoak, agitation for 10 seconds every minute using the "torus"
method recommended by Adams in The Negative, water stop bath for one
minute, fix for three minutes in rapid fix, followed by three minutes in a 2%
solution of PermaWash and a final wash in running water for 10 minutes.
Comments:
I will have to rate TMX at an EI of 40 and
develop for at least 11 minutes at 70°F. This method actually produced a lower
effective film speed than PMK, but Mr. King has
indicated that the higher speeds come with reduced agitation and lengthened
development time (also, the formula with 0.2 g of
phenidone should be more active than with
0.25 g of metol). Pyrocat produces a very
brown stain that is less obvious than the greenish
PMK stain. The negatives are very clean, with none
of the base fog that I get with PMK.
REFERENCE
Pyrocat-HD Film Developer,
Unblinking Eye,
Pyrocat-HD, Unblinking Eye,
Ed Buffaloe.