Pyrocat dilemma

Jim Noel · Mar 23, 2007

This morning I made up one liter of pyrocat hd 2:2:100. The stock is in glycol.

I used half of it to develop FP4+ for my standard time. The negatives appeared to be underdeveloped by about one stop.

AS soon as this group was hung to dry,I developed the film from the other side of each holder for the same time at the same temperature and rotation speed, etc. in the remaining developer. As far as possible there was no difference in the processing of the two batches.

The second batch of film is perfect.

Sandy, any ideas?

Could it be that the developer strengthened during the approximately 1/2 hour between uses?

Thanks for your ideas.

Jim

scootermm · Mar 23, 2007

sounds to me like a case of the working solution not being "mixed" adequately with the water... IE the 20ml of A and 20ml of B had not been adequately mixed in the 1000ml of H2O at first, perhaps causing the underdevelopment. Then after having been stirred and mixed up more sufficiently in the first developing session the working solution then adequately developed that second round.
I had experienced similar effects a while ago, and when I started thinking it through this is the conclusion I came to. So from that moment on, I would spend more time mixing up the working solution with my hands before starting development of my film. It solved the problem from that point on.

glbeas · Mar 23, 2007

The developer may have cooled down after pouring it into the tank, if the tank was not preheated with a prerinse. Another idea is the possibility of misreading the timer.

sanking · Mar 23, 2007

Jim Noel said:
Could it be that the developer strengthened during the approximately 1/2 hour between uses?

Thanks for your ideas.

Jim

Hi Jim,

No, the developer will not get stronger with time. It is very stable from the point of mixing, and at some point, several hours later, it will start to lose strength, though gradually.

The issue must be up front in the mixing, or in temperature control. Some kind of problem with the first batch is about all I can figure.

Sandy

Jim Noel · Mar 23, 2007

Thanks Sandy, that is what I thought.

The only difference I can think of is that perhaps my mixing prior to using the first half was insufficient. I did not re-mix prior to using the second half, but of course just sitting allows more dispersion. Temperatures were exactly the same at all stages. There is no cooling down because I develop at the same temperature as the water bath, which happens to be within one or two degrees of the ambient temperature in the darkroom at all times.

The difference in the highlight on the blue channel is .19.

Although I have never had this problem before, I think I will start mixing the developer prior to loading the film in the tank to help insure consistency.

juan · Mar 25, 2007

Jim, did you mix the Pyrocat yourself or get it from Formulary? I ask because I've just seen another photographer have a problem with Pyrocat glycol that came from PF. The cause of the problem is as yet unsolved, so I'm not blaming the good folks at PF - just still trying to track down what happened. In this case, the opposite occurred - the first batch was good, the second severely underdeveloped. The B solution had gone bad for some reason.
juan

Rick Olson · Mar 25, 2007

Hello Jim,

I processed a batch of 120 yesterday and mixed up 1000ml of working strength Pyrocat-MC (Glycol Mix). I was using a clear beaker and did notice that after I added Part A and B, the developer did settle in the lower half of the beaker. Had I poured only half of this brew into the tank, I am sure that I would have probably had a problem with underdevelopment. I used the entire 1000 ml and everything turned out fine. I guess my suggestion is if mixing up a working-strength batch for multiple sessions, make sure you stir thoroughly before use.

Rick

Jim Noel · Mar 25, 2007

I do not use PF pyrocat. I mix it myself so I have no one else to blame.
The two batches of film I have processed since the problem have been perfect.

sanking · Mar 26, 2007

juan said:
Jim, did you mix the Pyrocat yourself or get it from Formulary? I ask because I've just seen another photographer have a problem with Pyrocat glycol that came from PF. The cause of the problem is as yet unsolved, so I'm not blaming the good folks at PF - just still trying to track down what happened. In this case, the opposite occurred - the first batch was good, the second severely underdeveloped. The B solution had gone bad for some reason.
juan

I mentioned this to Juan in pm but let me say it here. Solution B of Pyrocat, whether -HD or -MC, is a plain 75% solution of potassium carbonate. Unless contaminated, this solution should last for several years since there is really nothing in it to go bad.

However, if Solution B were contamined with an acidic solution the pH might be reduced to the point where it would not work. You can always check a working Pyrocat solution for strength with a pH strip, dunked in the solution just after mixing and stirring. It should mesure in the 10.8 - 11.2 range.

Sandy King

Pyrocat dilemma

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