The reason I want to know is, sometimes I have sharpened knives and the edge felt really sharp, from rubbing my finger across it. But, regardless of how sharp it felt, it would not shave nor cut paper without tearing it.
Then, I have felt other edges, maybe just slightly sharper, that would cut newsprint easily, in any direction, and shave like a razor blade.
I am trying to find out what would be the difference in cutting width between a blade that feels feels sharp but isn't and one that really is very sharp.
I think the ones I have tested that felt sharp but wern't sharp was because I may have been feeling the small burr on the edge.
There is usually a very sharp edge under the burr, but the burr has to come off before the edge could be considered shaving sharp.
As far as geometery, and heat treating, the steel could be from a fine knive, or a wedge or an axe. Get it sharp enough and it will cut. If dull, it will not.
One thing I think would determine just how sharp it is possible to get an edge would be the type steel. Some steel has finer grain size than others, and the finer grain size steel would get the sharpest. If you had a way to measure grain size, this might tell you how sharp your blade actually is.
I have read that you cannot sharpen a grain because as the matrix of the blade gets very thin, the grains will tear out instead of sharpen.
I would guess that razor blade manufacturers and scapel manufacturers have done research on which steel would get the sharpest. The sharpest edge in these two applications would be the most beneficial.
What about one single layer from a damascus blade, one that has about 612 layers? One layer in a 1/4 inch thickness bar of steel would be very thin.
I have read the same article about the obsidian, and that is what got me thinking about how keen a very sharp edge would actually be.
