Brewing Pyrocat-M

Here are a number of quick notes on Pyrocat-M, a variation of -HD. The formula given by Sandy King follows:

To mix Stock Solution A,

|Distilled water at 50°C|750ml|
|Metol|2.5g|
|Sodium Metabisulfite|10.0g|
|Catechol|50.0g|
|Distilled water to|1000ml|

Stock Solution B is a 75% solution of Potassium Carbonate,

|Distilled water|750ml|
|Potassium Carbonate|750.0g|
|Distilled water to|1000ml|

That'll make a liter of stock solution each. I made up 100ml of each instead, dividing each amount by 10. The -M variation is supposed to add a touch of sharpness over -HD.

Solution A was easy to mix. Just add the various components in the order above. A slightly yellow solution resulted. Do be cautious when handling the Metol though. I experienced a mild irritation when mixing the powder, but it went away after scrubbing down. I have no problems with it in liquid form.

The Potassium Carbonate (K ~2~ CO ~3~) is tricky to store; my stock was packed in 250g sachets. It's highly deliquescent, which poses a problem when partial quantities are used. There's a slight vapor in the sachet now, but I don't think it'll adversely affect the rest of the stock. Sodium Carbonate is far easier to handle.

When mixed into solution, K ~2~ CO ~3~ appears to be rather cloudy, but it clears up in 30 minutes or so. That's apparently normal.

I stored them in brown glass bottles with a stopper. Apparently shelf life is 6 months or so. Using it at 1:1:100 dilutions should yield 40 rolls. It's extremely economical to use at around 10 cents a roll.

I developed a roll of Fomapan 100 in Pyrocat-M mixed to 1:2:100 dilutions as I prefer shorter developing times. 5m30s was a pretty good starting point, and produced rich negatives with good density. Looks like they'll print easily. For Fomapan 400, 7 minutes works well for me.