View Full Version : Pyrocat-HD and agitation

Mark McCarvill
22-Nov-2005, 16:22
I'm new to the darkroom and have been experimenting with Pyrocat-HD and home made BTZS type tubes. For images without significant amounts of smooth area such as sky, I've successfully used semi-stand and stand development to produce wonderfully sharp negs. For images that do have lots of sky, I've been trying minimal agitation – 1 minute agitation to start and then 10 sec every 3 min. My results have been disappointing. While the skies are even, contrast seems to have been reduced. I've posted an example here (http://www.stepwise.ca/pyro.jpg); the ground under the bench looks pasty and unnatural.

I suspect I'm doing something wrong with my agitation and would appreciate any suggestions (including the possibility that agitation isn't the issue). My agitation technique is to gently roll the tube in the water bath and then let it stand on end for the time between agitations. Other than the agitation schedule, everything is exactly the same with minimal agitation as when I do semi-stand and stand, which both work great but unfortunately create mottled and uneven skies.


John Berry ( Roadkill )
22-Nov-2005, 17:57
You didn't say what film you are using. Time and dilution. The shot to me looks like to much agitation for the ground. I use hangers with tanks I made out of clear acrylic. I'm shooting Fp-4. For semistand I use 1.5:1:200 72 degrees for 23min continous agitation first 1 1/2 min and 2 ASA agitations with 12 min left. Produces a neg DR of 1.6 for printing on new #2 Azo. My tanks use 1 ltr for 4 4x5 and 4 ltrs for 4 8x10.

Mark McCarvill
22-Nov-2005, 18:20
Hi John,

Here's the info ...

T-MAX 100
Pyrocat-HD 1:1:200
Temp: 70F
Time: 24 min (approx N-1), as follows: 1 min initial agitation, followed by 10 sec agitation every 3 min.

Are you getting nice even skies with your semi-stand technique, John?

By the way, what’s an “ASA agitation”?



Doremus Scudder
23-Nov-2005, 02:49

I don't understand your objection to the ground under the bench. To me, it looks too light and possibly too contrasty. This doesn't fit with your diagnosis of "reduced" contrast. Note especially the shadow of the bench leg on the ground, which is very light. So, maybe a little burning and/or maybe a bit of a reduction in contrast might give you tonalities that you like. It may also be possible that the ground under the bench is overexposed and blocked up a little. I'd have to examine the negative. Blocked highlights will give a bit of a pasty look, but this look can also happen when values are simply printed too light, i.e. on the toe of the paper, which has a tendency to make them block as well. Most modern films do not block up unless the overexposure is extreme.

Any agitation scheme that gives you even development is a good one. Don't think that contrast issues are related anything but indirectly to the agitation. Contrast with a given agitation scheme can be controlled by increasing or reducing the development time. Sounds to me like you need to keep the agitation scheme and redo your Zone System calibrations... The sky looks great.

Hope this helps some,

23-Nov-2005, 12:34
I've had troubles with skies when using one of the minimal agitation schemes, and others have reported similar problems. I never found a solution, so I have gone back to brush development for my negatives with large areas of smooth sky.