What Water Temperature when mixng pyrocat-HD?

[Andrew O'Neill]

ok ok ok...after being not too pleased with PMK and Rollo a few years ago I've decided to give pyrocat-HD a shot. After looking over the formula I noticed that no temperature was given for the water when mixing up the chemicals. What's the recommended temperature? Lets hope HD works for me.

[Andrew O'Neill]

It's okay! I found the temperature after doing a google search! It's 52 Celcius. Now it's down to the darkroom to mix up the stuff.

[Linas Kudzma]

Andrew,

I'm not sure where you found the recommendation for 52 Celsius, which is 126 degrees Fahrenheit (very hot water!). I mix and dissolve Pyrocat-HD at room temp.

[Mike Troxell]

According to the instructions from Photographer's Formulary, Pyrocat-HD (solution A) should be mixed at 125 F/ 52 C. Solution B can be mixed at 68 F. Thats how I always mix it.

[Michael Kadillak]

I concur with Linas. I mix it with a hot plate stirrer that is only modestly warm. The carbonate needs aggressive stirring and slow adding of it to get it all in solution. Make sure that you use a small volume pipet or a graduated cylinder to accurately measure the smaller quantities. Money well spent. Good Luck!

[Linas Kudzma]

I'll elaborate on my answer to clarify. I mix both solution A and B with no external heating. I use a lab stirrer with a magnetic stir bar. The components of solution A slowly go into solution pretty easily, while dissolving the anhydrous potassium carbonate of soluton B into such a small volume of water takes more time. The potassium carbonate initially clumps up on contact with water, but with sufficient stirring dissolves to a perfectly clear solution. You will notice that anhydrous potassium carbonate plus water generates considerable heat (exothermic) while dissolving. It might be easier to just dissolve the carbonate in double the amount of water and use a double amount of solution B.

[Andrew O'Neill]

Thanks! I mixed it up. Since I am mixing by hand I opted for the 52 Celcius temperature for solution A. My arm just about dropped off after slowly mixing all that potassium carbonate for B! I developed an 8x10 sheet of HP5+. I used my old rollo pyro data. Looks like I'll have to add about 25% more time. Thanks again for your help!

[sanking]

Andrew,

If you use the 2:2:100 diluition of Pyrocat-HD your development times should be almost identical to those of Rollo Pyro at 2:4:100.

You can find more mixing and develoment information about Pyrocat-HD rat http://unblinkingeye.com/Articles/PCat/pcat.html

Sandy King