Quote Originally Posted by philldresser
Just for interest sake my Pyrocat-HD stock solutions have given up the ghost Worked fine last week but completely dead this week

I hope Phil, you did not find out with film in the soup. If you did not lose any exposures, what was the test ?
Stock Solution A is good until it turns dark brown or black, and this appears to happen quite suddenly after about six months if there is only a small amount of solution left in the bottle. Full, or even partially full bottles are good for much longer, up to a year or perhaps even more. In any event my experience is that the solution is good as long as it is clear. Stock Solution B should last indefinitely.

Contamination of either Stock Solution A or B with minute quantities of the other will greatly accelerate aging and decrease the shelf life of the solutions. Therefore be especially careful when mixing the working solution to avoid contamination. I use dedicated syringes for each of the stock solutions.

However, if you are concerned about maximum shelf life consider mixing Stock Solution A in propylene glycol, a la Pat Gainer.