I've never been to chef school, so why do I think I can tell you more about sharpening kitchen knives than culinary experts can, and sometimes even go against their advice?
I've worked many years in tool rooms, with cutting and grinding devices
of all kinds, and with metals both plain and exotic. I probably know more
about working with metals than any chef alive. I'm also clearly a lot less
tolerant of dullness than most writers suggest you should be.
Photo © i0017.
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GeneralDull knives are frustrating, damage the food you are cutting, and are dangerous. A dull knife may skid unexpectedly and still be sharp enough to cut into you. If a knife is dull enough to "need to be sent out for sharpening" it has been too dull to use for quite a while. There is no excuse for dull knives. The pros have been afraid to tell you the truth - and the truth is this: you need to learn to sharpen your own knives, and you need to learn to do it with stones, and you need to do it early and often - and it isn't hard to do. If you can learn to slice thin, you can learn to sharpen knives. As "Exhibit A" I present my Mioroshi Deba. It has been used almost every single day for about 40 years, and every one of those days it's been wicked sharp. At its worst it would still do well with the "newspaper test". It has never seen a knife sharpener (I don't own one), nor has it touched a sharpening steel. Notice that for 40 years of use it shows rather little wear. Maintaining a knife like this is not difficult, and it's not tedious -
unless you have been negligant and let your knife get very dull. A prep
knife needs to be sharpened once or twice a week, depending on how much
you use it. A filleting knife may need to be sharpened after every fish,
and a boning knife should be sharpened after every use. If you cannot make
it totally sharp in just a few minutes, you have been trying to cut with a
very dull knife.
Sharpness Tests and Inspection
What you Need & Don't NeedYou Need StonesYou need two sharpening stones, one medium and one fine, and your cutting board. If you really abuse your knives or wait way too long to sharpen them you might need a coarse stone. Types of stone and terminology are complex and confusing, so rather than clog up this page with all the details I have made a separate page for Sharpening Stones . Both man-made and natural (Arkansas) stones will work fine, but man-made stones cut faster and natural stones aren't as good with stainless as they are with carbon steel. Some stones have a medium and fine side, but in most cases they are not ideally matched for kitchen use. The size you want is 2 inches by 6 inches by 3/4 inch or larger. Can't afford stones? There's a way around that on my Sharpening Stones page too. Lubrication will help keep stones cutting well and prevents them from becoming clogged with metal. The lubrication you want to use in the kitchen is running water. Oil is not only messy but the stone will not cut as fast. Experts have found that oil produces an inferior edge because it holds grit from the stone causing microscopic chips in the edge. Sportsmen use oil because water may not be available. I occasionally scrub my stones with a scouring kitchen cleanser (similar to Comet) to clear the pores and keep them cutting well. What stones would I choose? I like a fine India stone
used with water for aggressive edge shaping, but at 280 grit it's too
coarse for a finished edge. I like something around 700 grit for the
finish edge, a fast cutting diamond or water stone (I use a diamond
stone).
Controversial
Not Needed
How to SharpenIf you can learn to slice vegetables thin, you can learn to sharpen knives. The first thing you need to do is get a feel for sharpening angles. This will improve with practice. A thin vegetable slicing knife (Santoku or Nakiri) should be sharpened at a shallower angle (sharper) than a general prep knife, and so should a filleting knife. A meat cleaver should be sharpened at a much higher angle than a prep knife for a very strong edge. Back Angle & Edge AngleThe angles at the cutting edge are critical. The standard for commercial knives is a wide back angle of about 18° and a narrow (less than 1/32 inch) edge angle of 22-1/2°. This results in a very steep angle of 45° at the cutting edge, certainly less than ideal, but used by commercial knife makers to make a durable edge for those who never sharpen their knives (most people). Knife sharpening services will maintain these angles for the same reason. Note that Japanese knives angled on one side only (chisel edge) have an angle of about 25°. This results in an edge much sharper than the 45° edge of a conventional knife angled at 22-1/2° per side. Japanese knife makers also make their knives a bit harder to support this sharp edge.
Personally, since I sharpen my knives early and often, I like a
shallower angle and grind a back angle right out to the edge. This may
take a bit of effort with a new knife, but is easy to maintain once done.
Then I use a few strokes at a slightly steeper angle to create an
extremely narrow edge angle.
MethodWhile the same stones and general methods work for both carbon steel and stainless steel, there is considerable difference between the two.
Depending on the condition of your knife and its typical use you will usually start with your medium stone and then finish with the fine stone. If the knife is still quite sharp you may go directly to the fine stone, as I do with my Santoko. Generally you will hold the stone in one hand and the knife by its handle in the other hand. If you are unsure you can do this safely or accurately, you can place the stone on a folded up wet towel on your cutting board, but I find this awkward.
The upper photos show stroking one side of the knife across the stone, first at the start of the stroke, then at the end of the stroke. The lower pictures show the same for the other side. After a number of strokes across the stone on both sides, rinse the blade and make a firm cutting stroke across your cutting board. Make sure the full length of the edge contacts the board at some point during the stroke. What this does is break off the feather of a stainless steel edge, or at least weaken it and bend it over so far it'll be taken off by a couple more light strokes on the stone. For a carbon steel knife it will break off teeth that are too long and fragile. Repeat as needed, always making a few light strokes on the stone after the cutting board slice, until the knife easily passes the newspaper test - or simpler, just feels right when cutting. Note that every article you'll see tells you to stroke leading with the sharp edge - but I stroke with the sharp edge trailing. I'm very uncomfortable with leading with the sharp edge. Does anyone at all agree with me? Only the Japanese - but I've heard they know a thing or two about knives. Links
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