Conrad, I don't know if you're interested in any of this, but if you view the tech. data on the Kodak site, they have some pretty extensive tips about mixing Xtol. It almost reminds me of mixing up E6, the way they describe it. In addition to being sensitive to hard water, they give you the aim points for what the specific gravity, and the pH of a "correctly" mixed up stock (straight working) soln. of Xtol should be. Now, I haven't done any of this with my tank line, but I haven't had any problems either. The reason why I don't run TMX through this is that I am very used to the way TMX responds to TMax RS (it's what we run where I work), so when I ran it through my Xtol line, the results were a little different, and I like to be able to use developers I can predict. Which is not to say that Xtol won't work, it's just I like TMAX RS alot. Now, when I mix up E6, I worry about pH, specific gravity and water quality alot. If you look at the specs. for other developers like D76, T Max, etc. Kodak mentions nothing about this stuff up front. Now, it could be that in a process control manual, they have this info., but not on the general tech. sheet. What does any of this mean? I don't know, I'm not a chemist, but there has to be a reason why they list it there.(posted 8510 days ago)Ken, I have never seen that. Isn't PEC-12 usually used for non-water soluable marks? I was going to suggest that maybe you were picking it up in your wash water (or any other step), but since it sounds like it only happens with TMX in Xtol, I'm stumped.