We got a (non-fancy, ~US$5) Kai knife. It has a very thin blade, and is pleasantly sharp out of the box.
It needed sharpening after a few months of use, so I stuck it under the microscope. Turns out the blade has a very narrow and quite coarsely-ground bevel on one side (first photo: note coarse striations perpendicular to edge), and is polished flat on the other side. I estimate (just by eye) that the factory grind is about 250 grit.
I sharpened freehand on a DMT "fine" (~600 grit) diamond plate. I hold the blade at an angle to the surface of the steel plate (just habit), so the new grind marks are at an angle to the edge. The second photo shows polished (brighter) steel at the very edge of the blade as well as a bit further in, with the original perpendicular coarse striations in between.
This shows that the blade was originally hollow-ground on a grinding wheel (which is what one would expect). Because the bevel is slightly concave, the flat steel plate was able to wear away only the "high spots" of the steel on the edges. I could have switched to a coarse stone and worked the entire bevel flat, but that was not necessary. I just wanted a quick touch-up.
#knives #sharpening