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Re: Dull Razors



On Fri, 24 Sep 1999, Jim Green wrote:
Why do shaving razors get dull?

On my way out of school this afternoon, I grabbed a microscope and brought
it home to do a quicky examination of a couple razor blades. As I am
often reminded by you PHYS-L guys, physics is experimental science and I
try to remain true to that.

As I suspected, the "sharpness" of a brand new stainless steel blade at
the microscopic level was not as slick and smooth as one might expect, but
the edge of a used blade was absolutely devastated: relatively "huge"
chunks of metal torn away or bent aside, reminiscent of a lawnmower blade
that has hit many rocks and sticks. It would seem that hair and epidermal
debris must be a pretty rugged landscape for the microscopically thin
blade-edge to be repeatedly dragged through; and that hair and skin tissue
must present quite a degree of "hardness" at that scale.

As Bill suggested earlier, there may be different answers for different
types of blades; I only looked at my Gillette Sensor stainless.

Best wishes,

Larry

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Larry Cartwright, Physics and Physical Science Teacher
Charlotte High School, 378 State Street, Charlotte MI 48813
<physics@scnc.cps.k12.mi.us> or <science@scnc.cps.k12.mi.us>
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