TIL I undercut my toner for 3 months and got better gray coverage
I tried dropping to 10 vol on a client's gray blend in March and got cleaner deposit than my usual 20. Is this just luck with her hair, or is 10 vol the real move for gray?
Three months is enough time to rule out luck, so I'd say her hair isn't special. I see this same thing with paint at work, where two thin coats cover better than one thick one because a heavy coat slides around and dries uneven. Hair color and paint both follow the same rule: a big load of developer pushes pigment in fast, and a small load lets it settle where you put it. Her gray probably grabbed the 10 vol because the deposit stayed put instead of flooding past the cuticle. I'd keep testing it on a few more heads before you call it your new default.