View Full Version : Why I love Pyrochatecol

Jim Galli
2-Apr-2008, 10:11
bird shit hat

This isn't a picture that's going to make my name a house hold word. The hat in the windowsil has probably been undisturbed in this old mill building since perhaps 1933. Meanwhile the birds haven't been kind.

What's remarkable about this picture is this. A normal exposure if I had been standing outside those windows would have been 1/60th sec @ f32 which I used. The building is a cave inside. I exposed the hat for 45 seconds f32 and expected the windows to just be blown out. The fact that I got detail outdoors with that amount of over-exposure can only be attributed to the masking action of pyrocatechol. FWIW. For my style of shooting where I'm using antique lenses wide open in most any light, I think the PyroCat saves my bacon a lot.

Another example of what I'm talking about:

'35 Buick Verito

Here I used a Verito wide open out of doors this time. This was Adox 400 asa? (J&C 400)film while the first example was Tri X. The Verito was wide open f4. The exposure should have been about 1/2500th in mild overcast light. I gave about 1/5th with the old studio shutter.

OK, that's all the secrets I'm giving away for today. I'll grant that the negs are too thick and flat for Platinum prints in these extreme cases but they print easily on modern variable grade papers. Cake and eat it too?

Ed Richards
2-Apr-2008, 10:35


This is Tmax 100, Xtol 1:3. The white is sunlight on pure white lime mortar, the shadow areas are in deep shade inside a civil war era fort. Nothing special - extra exposure and shortened development, and the negative is thin enough to scan on my crummy consumer scanner.

Michael Heald
2-Apr-2008, 11:49
Hello! This sounds like the catechol developers give increased contrast in the highlights because of self-masking, like an inverted 'S' instead of the classic 'S' log exposure curve? Best regards.

Michael A. Heald

2-Apr-2008, 11:56
very instructive,
]and lovely pictures as usual-

2-Apr-2008, 12:18