From: Scott Wainer (smwbmp@starpower.net)
Date: 12/03/02-11:36:46 PM Z
Hello all -
I'm hoping someone out there can help with my problem.
Problem:
After reading "The Book of Pyro" and visiting www.unblinkingeye.com, I recently switched from Ilford ID-11 film developer to Pyrocat-HD with the hopes of getting negatives that have better tonal seperation, are sharper, and have less grain. I am currently performing film speed tests with Ilford Delta 400 (4x5) which I will use to create enlarged negs (via Liam's reversal process) for contact printing. I believe that I am getting excessive general fog; causing extreamly slow film speed results.
Processing:
I chose 15 minutes as a starting time and tray developed (with gloves) at a dilution of 1:1:100 (see below for formula); agitating for 15 sec. every minute. I used a water stop (2 min.) and fixed (2 min.) in TF-3 Alkaline Fixer without Sod. Sulfite. I then returned the film to the developer for 2 min. without a rinse, washed for 20 min., and dried.
Having a B&W densitometer, I could not get an accurate density reading from the stained film. Using the process for estimating negative density without a densitometer found in the Ansel Adams Guide : Basic Techniques of Photography, I did the following:
1. Print a very light tone using a unexposed, undeveloped piece of film cleared in fixer. I used the densitometer to measure the density of the print which I recorded along with the time (A) to make that tone.
2. I then printed an unexposed piece of film developed in Pyrocat-HD to the same tone as in step 1, using the densitometer to ensure the density of the print matched that the original. Again, I recorded the time (B) to make that tone.
3. Next, I printed a piece of film exposed for Zone I and developed in Pyrocat-HD to the same tone as in step 1, using the densitometer to ensure the density of the print matched that the original. Again, I recorded the time (C) to make that tone.
4. Finally I divided the times B & C by the time A to come up with the ratio for steps 2 & 3. I then compared the ratios for steps 2 & 3 against the Exposure-Density chart.
What I came up with was that the density for base+fog (neg in step 2) was approximately 0.22 and the density for exposure (step 3) was approximately 0.24. Assuming I need a density of 0.10 above base+fog for zone I, I would have to rate my film at EI 100 for a 400 speed film (a loss of 2 stops).
Question:
The newer version of Pyrocat-HD uses a 100% soln. of Pot. Carbonate - the older version used a 10% soln. of Sod Carbonate. Per Anchell's The Darkroom Cookbook, Pot. Carbonate is stronger than Sod. Carbonate - needing 0.90x the weight for subsitution. According to The Book of Pyro, pyro combined with a strong alkali (higher ph)increases base fog. Should I revert to the older formula? I also read that Ed Buffaloe (unblinkingeye) used a 10% soln. of Sod. Hydroxide (even higher ph). Does a 10% soln. of Sod. Hydroxide have a lower ph that a 100% soln. of Pot. Carbonate?
Plea:
Pleasssssssse, somebody set me straight. I will have to go back to ID-11 (sigh) if I can't straighten this out. I want it all - better tonal seperation, sharpness, and less grain at somewhere close to the manufacturer's ISO/ASA.
Thanks in advance from a newbie,
Scott Wainer
The Pyrocat-HD formula I use is:
Stock Soln. A
Sod. Bisulfite 1 gm
Catechol 5 gm
Phenidone .2 gm
Pot. Bromide .2 gm
Distilled Water to make 100 ml
Stock Soln. B
Pot. Carbonate 100 gm
Distilled Water to make 100ml
Diluted 1:1:100 with distilled water
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