Sharp is a misnomer. It is a catch-all phrase that best describes how easily an edge cuts.  A razor blade, or an Exacto knife we would all think as being super sharp....but that is not quite right.......they are very thin, so they will cut "easily", but in fact they would not be considered super sharp. Paper is not super sharp, yet we have all managed to slice ourselves terribly while wrapping a present.

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Sharp lets define as the "angle" of the two opposing sides of the edge. So a 15 degree angle ( like that on a straight razor) is sharper than a cleaver that may have a 40 degree angle. But that isn't the whole story....

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If the 40 degree angle Cleaver comes to an exact point ( in theory perfect), it may be "better" than the exacto with an really worn and rounded tip. Lets call the perfection at the tip its Keeness.....

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Now.....we all know Steel is hard and is difficult to bend right? But think about that perfect tip......how thin is it? If I told you it was thinner than tinfoil would your mind come to think of it as flimsy and delicate??......Well it is!

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So where am I going with this?...let me explain. You could sharpen a knife with a 10 degree angle...so the tip is very thin almost perfectly.....and after cutting a carrot in half......it would be almost useless.....its edge bent and broken and needing to be re-sharpened. On the opposite approach, we can sharpen at a 40 degree included angle, and although it may take just a wee bit more effort ( and I mean just a smidgeon) but that edge would cut 1,000 carrots......so you have to decide what trade-offs you are willing to accept.

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As a Professional Engineer, and a Chef at home, I have found the Science and Real-Life Theory in the kitchen very interesting to explore. My first rule is to sharpen an edge to match the use.....there is never a one-size-fits-all answer. Below are some SEM ( Scanning Electron Microscope) images of different levels of sharpness and keeness for you to see up close!

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