So I've sharpened all my knives and have developed good apexes and good burr removal. It's razor sharp, but how do I get that mythical edge retention that people are talking about? I can barely get through a few min of prep while keeping that scary sharp edge. Is a cutting board that I need or cutting technique? This is driving me mad. I have white steel, blue steel, super blue... all hair popping sharp but they all lose that scary sharp edge with in a few min. are my expectations too high? should I just accept the fate that I will have to hone them after a few min of use to restore the scary edge ?
There's many factors at play regarding edge retention yet in my experience with Japanese knives there are two things that most people do incorrectly to prevent themselves from achieving decent edge retention. (A
ssuming that all variables like using a good cutting board, good cutting technique, etc are good to go.)
1. Improper Burr/Wire Edge Removal
Most sharpeners just lightly stroke the edge on a fine stone/strop and call it done. I feel that if your edge is weak enough to flex like this using such light pressure then it's absolutely weak enough to flex under cutting pressure.
It's one thing to get a knife scary sharp, or make an edge pretty looking, but altogether another thing to make an edge that will last a couple of weeks of pro use.
When learning to sharpen I strongly suggest deburring after each and every stone in your progression. Pull the loose burrs off and get them out of the way so that the next stone can abrade/refine the edge. This means to pull/cut into a substrate that will grab the burrs and pull them away and off of the cutting edge without dulling the knife. Some use cork, wood, or thick felt for this.
2. Finishing With The Wrong Grit
For general purpose kitchen use I feel that going beyond a 5k stone to be problematic. Actually most 5k stones are too fine really but I have to pick a number to speak to, don't I? If too fine of a stone is used to finish on you'll have too fine of an edge, an edge with no "teeth" to bite into your product. Also worth noting is that it's VERY easy for the inexperience sharpener to wobble a bit and cut multi-faceted bevels and when this is combined with the use of polishing stones what you get as a result is a nicely rounded over edge with no bite and very slick. If the wobbler sharpener stops at a coarser grit he'll still have a multi-faceted edge yet his edge will have some bite still.
Use of a leather strop can lead to poor edge retention - if used incorrectly - that is with poor technique. Similar to the above mentioned wobble problem the incorrect stropping on leather will provide a rounded over edge.
Using chromium oxide on a strop will make for a frightening scary edge for sure, an edge that will slay paper towel yet fail on a tomato once the cutting board is touched. I believe this is because chromium oxide has rounded particles that polish the edge too much. *Note - chromium oxide can be wonderful for use on a yanagiba though, the level of sharpness and cut provided from this stuff, for this particular knife/task is crazy! A much better choice for the general use stropping compound is something like diamond spray as this stuff will scratch at the edge and provide a rougher cutting surface, even if more refined than that provided by the last stone used - a best of both worlds solution.
PS - Some level of scary sharpness, even the slightest bit, will be lost upon initial use - this is to be expected. What's not acceptable is a failing edge, an edge that doesn't cut after it's initial use.
