Mixed a gallon of Zone VI hypo (Calumet) on day 1 and used one quart. Noticed n othing unusual. Next day used another quart to fix 4 photos, each rinsed and pl aced in a waiting tray in another room with a bright light. Went off for an hou r and came back to find three of the four prints turning brown, the last one not yet. And the hypo tray liquid was a bright blue in color. Hmmm! Threw it out. Took quart #3 from the bottle and determined that it cleared film in two minut es so used it for four photos. At the end of the session found that the hypo tr ay liquid had a blue tinge but not as strong as quart 2. Anybody got any ideas? Did I get a package of hypo that was half hypo-clear per chance? That might e xplain quart 2, but not quart one that seems to have been OK. Or do I have anot her unsolvable scientific mystery here?