Pyrocat M - Brown powder residue?

[BarryWilkinson]

Two months ago I mixed up my first batch of Pyrocat M from raw chemicals. Most of the chemicals had been around for a while.

The first sheets I developed in the chemicals were very good. However, after use I put the brown glass bottles in a fridge as my darkroom as it gets very hot.

I developed some more sheets 3 weeks later and found a brown powder residue on the washed film and in the bottom of the processing tray after they were dry.

I have assumed that the chemicals have gone bad and will mix up a fresh batch with new chemicals. Has anyone else exepirienced this residue. I am a little concerned that if this re-occurs I will destroy some important negs.

Barry

 

[Tom Hoskinson]

Two months ago I mixed up my first batch of Pyrocat M from raw chemicals. Most of the chemicals had been around for a while.

The first sheets I developed in the chemicals were very good. However, after use I put the brown glass bottles in a fridge as my darkroom as it gets very hot.

I developed some more sheets 3 weeks later and found a brown powder residue on the washed film and in the bottom of the processing tray after they were dry.

I have assumed that the chemicals have gone bad and will mix up a fresh batch with new chemicals. Has anyone else exepirienced this residue. I am a little concerned that if this re-occurs I will destroy some important negs.

Barry

Were the solutions you put into the refrigerator the stock solutions? Were they the residual working developer?

In either case, as the solution temperatures decrease, the least soluble chemicals will tend to precipitate out of solution.

Recommendations:
1. Don't store the used working developer, use it as a one-shot, then dump it.
2. Store the stock solutions in completely filled brown glass bottles at 20 deg. C (or a bit higher).

 

[Gerald Koch]

It's oxygen that usually causes developers to go bad not the storage temperature. So refrigerating a developer really does nothing useful. However, lower temperatures can cause certain chemicals in the developer to come out of solution and it can be very difficult to get them to re-dissolve.

An exception to this is the case of Phenidone which is destroyed by hydrolysis in high pH developers. It's storage life can be improved by storage at low temperatures.

 

[BarryWilkinson]

Were the solutions you put into the refrigerator the stock solutions? Were they the residual working developer?

In either case, as the solution temperatures decrease, the least soluble chemicals will tend to precipitate out of solution.

Recommendations:
1. Don't store the used working developer, use it as a one-shot, then dump it.
2. Store the stock solutions in completely filled brown glass bottles at 20 deg. C (or a bit higher).

Thanks for your replies Tom and Gerald. It is the stock solution in which I'm experiencing the problem. I always use any developer 'one shot'.

I guess I will have to find somewhere to store the working solutions outside of my often very hot darkroom.

Thanks

Barry