I have just mixed up my first brew of pyrocat-HD. I had enough potassium carbonate to mix with 150 ml distilled water for the b solution. I too found that it would not dissolve ... i followed the advice from this thread and mixed it VERY slowly in very small amounts at a time, with de-ionised water and at 20 deg. The first few amounts dissolved perfectly but after about the 4th or 5th it became very thick and powdery. and i still had about 1/2 of the powder to put in!. In the end I doubled the amount of water and it all dissolved in less than a minute!
Now I'm ready to start testing - can anyone give me any approximate starter times and ei's for 120 pan f, delta 100 and HP5+ in tanks?