Hand Tools Archive

The point where scratches don't show up..

david weaver
Since I realized that the 1 micron scratches will show at the edge of all of these pictures if that is where the depth of focus is set, I wondered at what point I wouldn't see scratches at all in a microscope that relies on light. Since this is a metallurgical scope, it has a top light only and relies on reflection.

It looks like the answer regarding the wavelength of light is that purple is somewhere around 0.38 micron in wavelength and around double that for red.

So we should expect that if the 1 micron diamonds get a decent bite at the end of the iron, they will leave visible grooves. Whether a finer grade of diamonds does or doesn't will depend on contaminants and grading of the diamonds. No edge looks completely scratch free under the microscope.

I have stropped razors fairly hard on chrome oxide (graded) previously, and that does leave an almost perfectly smooth surface when it's fresh, but instead of seeing something that looks like a mirror pane, then you can see any contours left over from prior honing - even if they're tiny contours. It's like someone took a picture of a razor with scratches on it and then smudged the picture.

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