Why get hung up on microscopic images or level of polish on an edge?
When I was new to sharpening I was easily impressed by the results given by sharpening stones that provided a mirror polish with no scratches when inspected under the microscope. Over time I came to realize that some of these stones weren't as good as I thought and also that a mirror polish doesn't mean the knife cut better. I was hung up on chasing a flawed concept promoted by people who lacked working knowledge or who were selling goods. Once I let this notion go I was freed to chase a better cutting longer lasting edge. Yes a polished edge can correlate to a sharp edge but it doesn't mean the edge provided is the best for the task at hand and it certainly says nothing for longevity or strength.
Why get hung up on grit rating numbers?
When I was new to sharpening I would seek out the highest level grit available in honing compounds like diamond, cubic boron nitride, silicon carbides, etc. I was easily tricked by the marketing hype, and forum BS, that a higher grit number meant a higher quality cutting edge, this was wrong. I've learned that many of these compounds are valuable to us sharpeners however many make for shorter lived edges and even very poor edges. I've learned that shopping for the highest grit level is a flawed concept as the results have shown that I can, in many cases, get better longer lasting edges from lower grit rated compounds. In fact you must consider each type of compound at each grit rating level as a potential for being better or worse than one another as it's not always a safe bet or wise purchase to go with the finest grit available as you'll likely be buying a lesser edge for your knives.
In my time as a professional knife sharpener I've taken great lengths to ensure that I have the very best combination of abrasive products at my disposal and this had led to extensive edge testing. In doing so I've found many items and combination of items to not work nearly as well as I would have thought they would. I've learned some expensive lessons over time and with this knowledge I bring to you the suggestion to not get too hung up on these things.
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7 comments:
I could not agree more... the most important thing is finding the right edge for the task. Also, in addition to the edge longevity being reduced from higher grit synthetic stones and compounds, some of the feeling of cutting is lost too. This is something that is kind of new to me as a way of thinking, but recently i've been spending time in Japan with a chef friend (who specializes in cutting Fugu)... he happens to be just as much of a knifenut as i am, so its been really fun. He's taken the time to show me what it means when an edge is too sharp... too sharp, you say? Yes... when you cant feel what you're cutting, its really not a good thing. This experience has really changed the way i sharpen knives and has really reinforced the idea of the right edge for the task.
Great post Dave!!!
Long ago I came to thatway of thinking. Yup after buying high end stones and making wicked thin edges, my edges where sharp as heck but didn't last long. So, through trial and error I came up with a system that worked for me. Now my only high end polishes go to my straight razors :p I do polish behind the bevel on my kitchen knives, but the edges are usually around 3k and work very well for me.
We can read your post in many levels, some more technical and others more soul searching.
There is a similar article from Alex Gilmore (http://www.thejapanblade.com/sidesharpening.htm) which you may find interesting.
I think that one of the most crazy things about sharpening is that nobody yet has come to a solution to what sharp “is” or “when it is”. So, we are trying to achieve something that we do not know exactly, precisely how to define.
I think about a spear point done hundreds of thousands years ago with much less resources and knowledge than what we have know. That spear point had a tough task: It had to ram into a mammoth, hold in its point the pressure of itself, a flying pole, and while running into the thick animal. If everything was ok, it could or should be used more than once (limited resources, use them as much as possible).
These spear points were “fractured” stones from center to edge, where the edge is actually a facture. I don’t think they care if glossy or shinny, but they did care about defective fractures.
Sharp was: yes, it did ram into the animal, and the animal could not step on top of us.
In another hand, you may discuss if your sharp blade is proper to certain things, but most of the people who hold the same blade would not be able to know how sharp it is.
In other words, were you see sharp or dull, some other people will only see sharp.
So we can have a sensorial knowledge of sharp that is not easy to define in words. Crazy or not, I feel that only certain knifes “worth” to pursue an ultimate edge. Which is a cycle: it happens that the blades that have more “blacksmith” craft are actually the ones who achieve better stages of sharp.
I can relate that when you sharpen a knife is like running. And what I mean is that at one point, when running you forget you are running, free your mind, start sensing the process itself instead of the effort to do it.
When you are sharpening you start sensing what is a sharp edge, for what, how, etc.
I have found the stones, under my budget and use, that I like to use. But often I try to use the other ones, which keeps me in check of what is it that make one or others more productive or to where I want to get.
Dave - I'm sure you are right - a mirror finish with a 30,000 grit Shapton would be fine for some tasks (mainly those where the blade pushes straight through, perpendicular to the cut object), but a coarser finish - 1,000 grit - with a relatively jagged edge (at the microscopic level) might be best for cutting meat with a slicing motion, with its vast variety of meat fibre types and directions - and cutting board surfaces.
Dave, What sort of "extensive edge testing" do you do?
I'm fortunate to have a lot of customers who work in professional kitchens. These folks have been the core testers that I use to get feedback on edge quality when I'm trying something new be it product or technique. I do my own simple testing as well but nothing trumps the feedback supplied by the professional chef/cook.
I agree with gist of the above comments.
As both a woodworker/woodturner and keen Japanese kitchen knife user/sharpener I get to use a lot of different blades for different purposes.
Push action cuts require different edges to slicing cuts, the latter benefiting more from micro serrations.
In heavy cutting applications like woodturning, where a sharp edge may only last a minute or less before needing to be resharpened, the investment in sharpening time has to be balanced against the time a sharpened edge will last in use. Anything more than 30 secs to resharpen for a minute or so of use is unacceptable. A much finer edge that may take say 5 minutes to achieve and last twice as long (3-4 minutes) is unproductive. More frequent but quicker 'rough' grinds on a bench grinder is the sweet spot.
However, I will happily spend an hour or so sharpening my Japanese hand forged kitchen knives on my various synthetic and natural waterstones (10 syn and 4 nats) to produce an edge that will stay sharp and be a pleasure to use domestically every day for many months.
But I imagine my kitchen knives would only last seconds if I was to use then for woodturning... :-( Different cutting applications need different types and levels of sharpness.
Having used natural waterstones on my kitchen knives for a few years now I firmly believe that the micro-serrations they produce are more durable. I also prefer the feel while sharpening and in use. But, I may just be justifying the cost... :-)
As with my woodturning, there is unlikely to be a productivity return in the professional kitchen for such things as natural waterstones or for that matter anything over about #4000-6000.
Neil
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