If you just use vinegar it will leave a very even discoloration. If you use the Mustard, "They" say to dab your finger into the mustard and then dab it on the blade. And repeat over and over. DON'T try and get it all even, leave some thick and some thin and con't completely overlap. The vinegar will take care of that (let the mustard dry for I have heard from 2-8 hours) then do the vinegar thing and let that set for 15-20 minutes and rinse.