Like the title says, why do sharpening stones dish out? It doesn't matter if you consistently use the entire surface of the stone, it will always dish out in the middle. The answer may be very simple but I'm wondering why?
Umm, this might be just too simple, but my guess is that you cant't effectively and ideally use entire surface of the hone, unless you're a robot? Some strokes are started (and finished, too) closer to the end, some further - and it all comes to
I think and I'm not an expert whatsoever it's because the center gets most "use" .
the center is always in contact with the knife/razor and the sides are less in contact with the knife/razor.
more contact means its more worn/more particles(garnets or glass) get used so they dish