Jeremy - I didn't see this the first time around. Yes, I routinely clear my gumovers in potassium metabisulfite to get rid of any residual dichromate stain (didn't I send you a PDF of my gumover manual?). That said, dichromate stain seems to be a function of your water supply or some other local variable(s). I never get it and don't see any visible difference after clearing, but I clear anyway just to be sure. Other gumoverists I know in Houston and Santa Fe get the stain routinely.