Does anyone know how sharp you can actually get a knife edge? I am asking about steel knives.

Also, does anyone have any idea on which steel will get the sharpest.

The reason I ask is because I have read that steel has grains in it, and the finer the grain, the sharper you can hone it, but that you cannot sharpen a grain. It would seem logical, to me at least, that the finer/smaller the grain, the sharper the blade is capable of getting.

Also, I have read that about 2 or 3 microns width is about as sharp as an edge will get.

Anyone have any input on this?