All the pyro formulas I've used have stained with a yellow-green stain. But pyrocatechin formulas have a stain that brown to black. I recommend you try Pyrocat-HD, which was specifically developed as a substitute for PMK. The formula and what other info I have can be found at:(posted 8556 days ago)http://unblinkingeye.com/Articles/Pyrocat/pyrocat.html