Pyrocat-P/Pyrocat-M

sanking · Mar 24, 2006

Silverpixels5 said:
Sandy:

Do all three developers give similar effective film speeds? I would always get box speed or better with Pyrocat HD, and was just wondering if the -P and -M variant do the same. Thanks!

I am not absolutely sure about this yet. Exposure and control of development must be virtually perfect to get a valid comparison of EFS. Even minute changes in the shape of the curve in the toe section can have a significant impact on EFS when you plot the data. My comparision test to this pont suggest that Pyrocat-HD gives a very slight increase in EFS over the -M and -P variants. But it is very slight, no more than about 1/6 or 1/8 of a stop. But these findings are far from conclusive and future tests may result in a re-evaluation of this finding.

Sandy

User Removed · May 11, 2006

Sandy,

I find the liquid pre-mixed Pyrocat-HD from Photographers Formulary to be very useful, since its difficult for me to mix dry chemicals in my home. I have always been pleased with the result of HD when using in my rotary processor, but if I could get sharper negatives...that would be great!

I'm wondering if these new Pyrocat formula's will be available in liquid form from Photographers Formulary.

Thank you,

Ryan McIntosh
www.RyanMcIntosh.net

Vlad Soare · Feb 8, 2010

Hello,

I'm looking for an inexpensive staining developer that has a reasonable shelf life, is easy to mix, and works well in a rotary tank. I had decided to give Pyrocat-HD a try, but then stumbled upon this thread. This Pyrocat-M looks more attractive to me than the HD, simply because I happen to have lots of metol in stock but no phenidone (and even if I did have any phenidone, I'd still prefer the metol anyway ).

I don't have any sodium metabisulfite, potassium carbonate and potassium iodide, so I'm thinking of using the following formula:

Solution A:
metol 2.5g
sodium sulfite 13g
pyrocatechin 50g
water to make 1l

Solution B:
sodium carbonate 200g
water to make 1l

Working dilution: 1:5:94.

Will this work just as well as the original formula? I'm planning to use it with 4x5" sheets in a Jobo tank.

Thank you.

Ian Grant · Feb 8, 2010

The Solution A will not keep more than a day or so if that with no Metabisulphite, Pyrocatechin oxidises very quickly and once that happens stains film heavily, and patchily. Metabisulphite is a strong anti-oxidant, it's used in the food trade so is usually easy to find. Ascorbic acid can be used instead.

Ian

Vlad Soare · Feb 8, 2010

Thanks, Ian.
What made me think of getting away with no metabisulfite was Sandy's comment on the first page:

I strongly recommend you add sodium metabisulfite (or sodium sulfite at a 13:10 ration with metabisulfite)

That's why I assumed that 13g of sodium sulfite instead of the metabisulfite should be OK.
You mean this isn't going to work?

Ian Grant · Feb 8, 2010

As a developer it'll work just as well with the increase in Sulphite, Metabisulphite forms Sulphite in an alkali solution anyway.

But in terms of storage it's the lower (more acidic) pH approx 4.3 of the Metabisulphite and the free SO2 it gives off that also helps protect the Pyrocatechin from oxidising, plain Sodium Sulphite will be around pH8.

Metabisulphite is often added to powdered paper developers to protect the developing agents during storage, Microdol-X, Bromophen are two examples.

Ian

Vlad Soare · Feb 8, 2010

I see. Thank you.

Vlad Soare · Feb 8, 2010

I've just remembered that I happen to have some potassium metabisulfite. I had forgotten about it because I've never used it. Do you by any chance know if this could replace the sodium metabisulfite, and if so, in what ratio?
Thanks.

Ian Grant · Feb 8, 2010

It can be used as a direct substitute, the same weight.

Ian

Vlad Soare · Feb 9, 2010

Thank you.

Pyrocat-P/Pyrocat-M

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