I concur with Daniel Taylor's comments. Because of all of the warnings on Xtol I am overly cautious. I did experience something yesterday that was unusual while mixing a 1-liter batch. I have been using the same plastic stirring rod(Kodak I think) for many years. Of course it has become stained from use. While mixing part A I noticed some unusual brown specks in the solution and it wouldn't disolve and the solution became somewhat discolored. The only source for this stain was the stirring rod. I discarded the solution, thoroughly cleaned the stirring rod and started with a new pack with no problem. I don't know if this might be a source of the "sudden Xtol expiration" problem but it was an eye-opener for me. I must be more careful in cleaning my equipment.(posted 8588 days ago)