A knife is not just sharp; it must be thin
In short: Most people think sharpening is about honing an edge, but the real physics involves reshaping metal. If a blade is too thick, it functions like a chisel rather than a cutter. To achieve a true edge, you must systematically remove excess steel to reach the necessary thinness.
The fundamental goal of using a sharpening stone is to reduce the thickness of the metal at the blade's edge. A knife is essentially a very thin piece of steel designed to split material; if it becomes too thick through use, it loses its ability to cut effectively. Sharpening stones serve two primary purposes: they take and reshape the edge, and they thin that edge back down until it is sharp enough to perform its function.
Different stones offer different trade-offs in speed and finish. India stones are harder materials where the brown side is considered finer; these require oil for use, making them a messier but traditional option. Alternatively, Crystolon stones can be used dry. While coarse sides of these stones remove metal faster to produce a rougher edge quickly, they lack the need for lubrication. The process moves from establishing a 'V' shape on the coarser side to smoothing and polishing on the finer side.
Technique is critical to avoid an offset blade. Experts recommend alternating sides rather than completing all strokes on one side first, as the backhand is typically less consistent than the forehand. To maintain a centered bevel, you should move from the heel of the knife across to the other side with consistent pressure. A simple mental model for the correct angle involves imagining filleting the top off a large cube of butter.
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- Summary by Intellect · source: How to Use a Sharpening Stone | Knives
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