Film Processing and Equipment Main Page
Pyrocat HD: Purchased from the Formulary. I considered purchasing the raw chemicals but storing bulk chemicals can be risky in terms of quality control. The kits are adequate and inexpensive enough for my purposes. Anyone wishing to use the Pyrocat is advised to read the article at the link below, written by the inventor, Sandy King, before proceeding.
http://www.unblinkingeye.com/Articles/PCat/pcat.html
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Pyrocat-HD |
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Stock Solution A |
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| Distilled Water |
750 ml |
| Sodium Bisulfite |
10 g |
| Pyrocatechin |
50 g |
| Phenidone |
2 g |
| Potassium Bromide |
2 g |
| Water to make |
1000 ml |
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Stock Solution B |
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| Distilled Water |
1000 ml |
| Potassium Carbonate |
1000 g |
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To make a standard
working solution mix 1 part A with 1 part B * Or substitute 25 grams of Metol (with a slight loss in film speed). |
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The mixing of solution A was straight forward, I used distilled water. It is recommended to mix the phenidone with a bit isopropyl alcohol, although I had no trouble with the small kit. The larger kit will have more to dissolve. Anyway I use a magnetic stirring heating plate so my hands don't get tired. Wear gloves and watch the ventilation, the Pyro is nasty stuff get it dissolved ASAP.
Solution B, potassium carbonate, was the most difficult to mix, it is almost a super saturated solution, so mixing needs to take time, small amounts and a lot of stirring. It took almost 20 minutes to get it all in, then another 10 to get it all dissolved. Be cautioned that the final solution will increase about 10-15 percent. There is also an exothermal reaction
Sandy King wrote:
I will also recommend my own Pyrocat-HD formula, a staining developer based
on Pyrocatechin/Phenidone. It is less expensive to mix than PMK and ABC+ and
works in place of either of them: a 1:1:100 dilution of Pyrocat works almost
exactly like PMK 1:2:100 (both in terms of development times and curve
characteristics), while diluted 2:4:100 it replaces ABC+ (and is even superior
to it for zonal expansion of tough films like BPF and HP5+). Pyrocat also is
much less likely to stain film than pyrogallol based developers like PMK and
ABC+ which must be used with rotary processing with great care.
Normal Agitation — Normal agitation for tank development is considered to be continuous agitation for the first 60 seconds of development, then agitation for 5-10 seconds every 30-60 seconds thereafter. With this pattern of agitation Pyrocat-HD can be used with no modification to your normal development procedures for conventional developers.
Minimal Agitation — Minimal agitation consists of continuous
agitation for the first 60 seconds of development, followed by 10
seconds of agitation every third minute. With this method a pre-soak of
five minutes is strongly recommended to avoid the possible formation of
bubbles on the emulsion. Minimal agitation has three desirable results:
1) it gives great apparent sharpness through the formation of maximum
adjacency effects, 2) it provides a compensating effect, and 3) it
provides increased emulsion speed.
With minimal agitation you should extend development time about 50% over
the normal time required for intermittent agitation, but experiment
before risking valuable negatives.
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FP4+ Development Stats: Two reel stainless steel tank, inversion and twist agitation.
1. Pre Soak 1 minute 2. Pyrocat 1:1:100. I use 5ml A and B per two roll stainless tank. 3. Stop with water, four dumps. 4. Fix 5 with Alkali based fixer. 5. Wash 15 minutes 6. Photo flow 30 sec 7. Hang dry
Densitometry - Measurements can not be taken with the Macbeth TD-502 because of the staining effects, a blue channel needs to be used. I purchased a Macbeth TD-524 and can now make density measurements for Pyrocat HD. My initial results are interesting and will cause me to reevaluate my development times. I also discovered one of my sink thermometers to be three degrees on the low side which only affected some recent tests.
Best development times for FP4+ ASA 125
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Ongoing Development Notes:
3/28/04 - I tried semi-stand development for FP4+, measured 2ml A and B for single stainless tank of 250 ml. Developed light agitation for 14 minutes, all frames barely developed. Likely not enough developer for volume of film.
7/8/04 - Sink thermometer off by three degrees. Some recent tests I thought were 70 F were actually 73.5 F. Corrections made. Purchased Macbeth TD-524 for stain measurements. Made initial tests with FP4+ using color densitometer and B&W densitometer. Results comparable between the red channel and B&W densitometer. Time should be increased by at least 50% for next test and/or dilutions increased. Film speed reduction may also be necessary if full tonal range is desired.
7/15/04 - Film speed restored with decreased dilution (2:2:100) and increased development time.