I am having a problem on which the chemistry sleuths out there may be able to shed some light. I have been running BTZS tests on FP4+ and TMY-2 in Pyrocat-HD and MC using both constant agitation (in BTZS tubes) and extended minimal agitation (vertical in tubes) techniques, both at 68F. I am reading the densities with the blue and UV lenses of Gretag Macbeth D200-II for use with Azo and Pt/Pd. With the FP4+ I am getting results that correspond with what others have reported, except that the MC B+F is slightly higher. With TMY-2 I am getting terrific results with HD using EMA. The results so far with the MC is another story. The first run EMA negs in my homebrew MC were thin for the short time (20 min.) and thin and seriously fogged and uneven for the 40 min. time. I have a PF bottle of MC, so as a control I ran a test using that - same result. Thinking that my homebrew and the PF MC might have gone off, I mixed a fresh batch of homebrew (heating the glycol to 250F) - same outcome. Thinking that something might be going on at the 250F mixing temp, I next made a batch using the lower temperature method. I haven't done an EMA test with that batch, but a constant rotation test of one sheet of TMY-2 at 15 min. gave me B+F of .15 (blue) and .43 (UV) which seems high to me. BTW, the HD I am using is also homebrew. Since both the HD and MC were made with the same catechol, that shouldn't be the problem. Since the MC is working OK with the FP4+ (except for the slight elevation of B+F vs. the HD) it seems that the metol is OK. Could the ascorbic acid be bad? That's the only thing I can think of.