I've had water spots appear on blades from my city water. If you've not had that with other blades it may have been the blood. I'm a pro tattooer and when we used to re-use our needles, and carbon steel at that, it was amazing how quickly blood will eat into steel if it isn't removed immediately. The metal polish will remove the gold wash whether it removes the stains or not. Read my sig below and you'll have less nicks if you take the old barber's advice.