I would like to learn more about what's happening with a kitchen knife edge when you try to take it as far as possible with your equipment. During the past 9 months, I have been getting ever more familiar with my Konosuke HD2 gyuto and my sharpening kit (Bester 500, Beston 1200 and Arashiyama 6000) and I also started exchanging knives and sharpening tips with a friend of mine who owns a pair of Moritakas and a Tanaka gyuto. At one point I gave him my knife with the best edge I could put on it and he would would compare with his knives that he also sharpened to the best of his abilities, and then he gave me his knives and it was my turn to compare. This exchange continues. I am finding quite some differences between how sharp can a Konosuke HD2 be compared to Moritaka Blue 2 when sharpened by the same person. When we last did this, it appeared the Moritaka will take a sharper edge and will retain it longer as well, or that it will wear down more gradually and evenly.
Recently I have built asymmetry in my Konosuke (I would judge it 70:30) and polished the hell out of it with my Arashiyama 6k stone, followed by stropping with these pastes: http://www.highlandwoodworking.com/mediumfinestroppingpaste.aspx The included angle could be between 20° and 25° - I went thin.
The results were stunning, the knife was screaming sharp, more then ever before, it shaved my forearm effortlessly. Yet, the edge was not very durable, for instance after I chopped some herbs with it on a wooden board (rocking motion), the curvy part of the blade which gets the most pressure during rocking almost stopped shaving after just one cutting session. It went from "hairs are bursting into the air" to "I need to put pressure to produce any shaving effect at all". All that in 5 minutes of time. Would any of you have an idea what might have happened there?
When I retouched the edge with Ara 6k, the knife instantly started shaving again (although not as well as after the strop). The episode left me puzzled.
My theory is that I had actually developed a wire edge by the strops that was good at shaving, but as soon as I went to the board, I have bent that wire and the knife lost its acute sharpness at once. Of course it still cut onions etc. with ease, but all lasers do. I couldn't see the wire or anything, I am only judging by the behaviour. My first thought then is to either stop polishing at 6k, forget about the strops and be content with it (the edge retention is better with stone-polishing only). But I like sharpening and getting to the bottom of things and I want to go further with my polish, so my second thought is to ditch the pastes and buy a yet finer stone (my hot tip is Gesshin 8k BDL used to praise over Naniwa Pure White which would be my second choice, anything else? Nubatama Bamboo?).
But maybe I made the angle too acute and it is not meant to hold? What could be the reasons behind the symptoms described? In the end, I would like the HD2 Konosuke retain its effortless-shaving sharpness even after some cutting has been done.
From various comparisons with the Moritaka Blue 2 I almost started to believe there is a limit to where you can take the HD2: as if it was only able to get "scary sharp" for a very short time, then it would dull to non-shaving level, yet still "quite sharp + lasery properties" and then it would sit there for a very long time before it would take the next step and get dull proper. As if the HD2 was meant to be more *thin* than *sharp*, if you know what I mean. Whereas the thicker and heftier Moritaka had a more linear dulling curve in time: it would be super screaming sharp for quite some time, and then would dull and dull evenly without a flat time period of same perceived sharpness until, also, it would become just dull.
I can't quite get my head around these characteristics and there is always the fact that I am no master sharpener and might have done many mistakes in both my technique, observations and conclusions. I would welcome a seasoned sharpener to shed some light and basically talk to me about what is happening in that micro-minute area of the cutting edge when it comes to different steels and different sharpening/polishing techniques.
Thanks a mill,
Edited by Machalik - 9/19/14 at 9:22am