I'm not going to postulate that my experience is the definitive answer, but as Richard K. pointed out, this has come up in a number of forums over the past few years. One discriminator seems to be that mixing the stock and working solutions with distilled water makes a difference. My recollection of earlier discussions was that people who mixed with tap water were the ones who experienced the early death of their Xtol. I recall that everyone who mixed with distilled water said they had never experienced this problem; and a Kodak representative weighed in on the discussion and said that ALL chemicals were designed to be mixed with distilled water because the variability of tap water around the world was WAY too much for manufacturers to plan/compensate for. I used Xtol for a couple of years before discovering Pyro (which I use now) and experienced the sudden death syndrome once, when I mixed it with tap water. I KNOW that someone is going to reply to this and say they ALWAYS mix with distilled water; and ALWAYS use clean equipment; and they have experienced the subject syndrome. So, let me just add that using distilled water and absolutely clean equipment is the process chemists use to ensure consistency in experiments and production. As photographers we risk a measure of inconsistency if we don't at least follow those proven processes. I'm not here defending Xtol, but I know that many photographers use tap water to mix their chemicals, including stock solutions. All I'm advocating is minimizing the variables. Bob Younger younger@xxxxxxxxxxxxxxxxxxxxxxxx > Well, you see what happens when Xtol dies. It doesn't > turn yellow, but rather it barely develops film. I > recommend testing with a film leader before development if > the Xtol is more than a few months old, or if it was > stored in a questionable manner. I'm sorry to hear about > your problem. A similar thing happened recently to me > using PC-TEA. >