Pyrocat HD

[BarryWilkinson]

I mixed 1000ml of Pyrocat HD A + B about one year ago. It appears to be working just fine but one two of the last negatives recently processed recently have one small chemical/mineral spot on the emulsion. Not significant but I am wondering if my solutions are getting stale? Both, but particularly Solution B are showing chemicals coming out of solution. Should I try to dissolve these on my stirrer or leave well alone?

Solution A was dissolved in Glycol, Solution B in bottled spring water. Finding distilled water is difficult around here (UK). Both bottles are topped up with inert gas after use.

Thanks for any advice.

 

[juan]

you're probably at the end of life on the B solution. Rather than mix a new B solution compute how much carbonate is in your volume of mixed developer. Then mix the appropriate A solution with the mix water and add the appropriate amount of dry carbonate.
Juan

 

[Andrew O'Neill]

And here I was thinking that solution B's life expectancy was indefinite!

 

[john_s]

And here I was thinking that solution B's life expectancy was indefinite!

It's a quite concentrated solution, maybe near saturated. It may be that at lower temperatures the potassium carbonate will crystallize. Mine is fine after a few years, possibly resulting from the moderate temperatures here indoors.

 

[juan]

I've seen solution B go bad.

 

[BarryWilkinson]

you're probably at the end of life on the B solution. Rather than mix a new B solution compute how much carbonate is in your volume of mixed developer. Then mix the appropriate A solution with the mix water and add the appropriate amount of dry carbonate.
Juan

Thanks Juan I had not thought of doing that.

 

[BarryWilkinson]

Thanks all. The average winter temperature in my darkroom is around 12C but it does look like the carbonate is coming out of solution.

 

[Brook Hill]

Thanks all. The average winter temperature in my darkroom is around 12C but it does look like the carbonate is coming out of solution.

Could try zapping it in the microwave Barry.

Tony

 

[Gerald C Koch]

The amount of carbonate used for solution B is close to the maximum that will dissolve at room temperature. It will always cause problems when the temperature drops. Use half the amount to mix solution B and then twice as much of B when you make a working solution.

BTW a microwave used for food should never be used for chemicals.

 

[BarryWilkinson]

The amount of carbonate used for solution B is close to the maximum that will dissolve at room temperature. It will always cause problems when the temperature drops. Use half the amount to mix solution B and then twice as much of B when you make a working solution.

That's a great idea Gerald, thank you very much.