Jorge is right on with his comments. The ratio of metol to catechol is too high to benefit from the unique qualities of catechol, even though catechol and metol are mildly superadditive. My guess is this formula stains very little, if at all. This is because metol is doing most of the work and the catechol is not oxidizing enough to provide the staining byproducts of oxidation. In part this is due to the ratio, but also because the alkaline component (carbonate) is not high enough to sufficiently activate catechol in this formula. If you reduced the metol to 1 or 2g, and extended your developing times roughly 50%, you would begin to see the potential of these components.(posted 8456 days ago)A more modern and well regarded formula is Pyrocat-HD. It uses 5g cat, 1g metol, 2g sodium bisulfite / 100ml distilled water; this is combined with a 100% solution of potassium carbonate (100g/100ml H20), mixed at 1:1:100 with water. Development times are between 10 and 13 minutes. There is an alternative formula for Pyrocat-HD which calls for phenidone in place of metol. You can find the details at www.unblinkingeye.com