The phenomenon you describe is one I have experienced with both TMX and 100 Delta developed using Xtol in a dip-and-dunk machine under extremely tight control at a professional lab. However, I would characterize it as yellow more than brown. The big problem this presents is that a non-proportional coloration results. There is virtually no effect on low negative values, and a signficant shift in areas starting at roughly 0.9 gross density. If one attempts to print these negatives on graded papers, highlights are very blown out, and can't be controlled by selecting a lower overall paper contrast, since the negative's curve shape (as read through a blue densitometer channel) is so strange. Printing on multigrade papers also presents problems, though the situation isn't quite as bad. Green density readings aren't as significantly distorted by the yellow stain, but they do still increase non-proportionally.(posted 8857 days ago)When an article on the genesis of Xtol appeared in Photo Techniques magazine last year, I wrote to the authors asking about this problem. They replied with an explanation concerning the depth of emulsion which gets exposed at higher light intensities, and how this would result in the yellow color with certain films. The specifics are at home, not here, so I can't give more detail from memory. Should anyone be interested I'll post an expanded summary tonight. Most important, however, was the author's statement that he realized he was offering an explanation of, not a solution to, the problem. My solution: I've bitten the bullet, bought a Jobo, will use ice in the summer to keep things at 75 degrees, and now process TMX in T-MAX developer. I had relied on the convenience of a lab, but Xtol's siren song of long life and virtually infinite replenishability took away that option. If you want it done right...