[bodybump]

Originally Posted by CanuckRolex

that mark is plastic left on the metal, not the plastic scratching the metal.

Plastic cannot scratch metal. It is physically impossible. Now sand or material being caught into the toothbrush will do it, but not the bristles themselves. This is like saying a car wash mitt is scratching your paint when it is actually the material caught in it causing the swirl marks.

I just did what you said and there was a mark, but under the microscope it is the ruler leaving plastic on top of the metal, not scratching into the metal. The plastic them wiped off with no mark after a small rag with some alcohol on it.

this is because the metal is harder that the plastic. You would see the same mark on a ceramic plate if you rubbed a piece of metal on it. Until a hand lnse the mark is metal leaving a deposit on the ceramic plate, not scratching into it.

Its kind of like the use of a pencil.

Very well said!!!