Sharpness and Sharpening: A Makers Year 14

Ohhh… This is going to be bad.

You know more tosh has been written about sharpening woodworking tools than a grown man can tolerate. But I shall proceed, but only if you are sitting comfortably.

There is a convention that sharpness is the product of two polished surfaces brought together at a suitable angle usually somewhere between 25 degrees and 30 degrees. Pedants may disagree, but I do not give a hoot.

Polished surfaces are generated by using a course abrasive, then a a grade finer, then a grade finer. The objective of each stage being, to remove the scratches of the previous layer. O K, so a shine in this context would the objective, yes? The more scratches removed, the more polished and shinier the surface would become??? I have used a shiny surface to a chisel back or plane blade back as a sign that I have done a good job for years.

Apparently this is just not so.  Look at the image below this is a surface created with an 8000 grit Japanese Water stone. this is the kind of polishing stone I and many other Western Woodies have been using for years. they are fast to cut relatively cheap and they give this great result.


So whats the problem? Well look at the second image below. This is the same tool polished with a NATURAL Japanese abrasive stone. The scratches are finer that is clear. What is confusing and counter intuitive is that the surface is NOT so shiny.



Tomohito -san who has been my guide on this has been trying to convince me that shiny is not automatically sharp and this is his proof. I have been using a couple of natural stones on plane blades for a while and can report a real difference in performance. They cost a lot more than man made water stones. My stone was about £300 and I only use it in specific situations where I need a surface “from the Tool” .





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