Dull 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
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
- The Newspaper Test
The real test of sharpness is, of course, how the knife feels in actual
use. You might, however, want to check it while sharpening, and this is
an imperfect but reasonable test.
Dry the knife blade completely. Take a quarter page of newspaper, and
fold it over. Crease it only where you'll be holding it. Starting with
the handle end of the blade just in front of your fingers draw the knife
across the paper at moderate speed in a single smooth stroke as you slice
downward. Use very light downward pressure. As in the photo, the blade
should cut, not tear the paper.
How far you get before the paper starts
to tear is a reasonable measure of sharpness. Ideally, a long knife should
cut right off the edge and a short knife should cut until the tip clears.
- Visual Inspection
With a strong light above, hold the knife so the sharp edge points
directly towards the light. Looking directly down at the edge, and moving
the edge about just a little, it should be entirely invisible. If there
are any glints of light from it, it is nicked or dull.
- Finger Inspection
Hold the knife by it's handle in one hand. With the other hand, place your
thumb on one side of the blade, your forefinger opposite it and draw your
fingers slowly straight off the edge. If you feel any burr at the edge on
either side the knife is plenty dull. Check this at various points on the
blade. You can feel burrs that are too small to see.
You can also perform this test by running a fingernail off the edge and
see if it catches on a burr. This test is very effective to see if you've
stoned all the way to the edge when reshaping blade angles.
Another "finger test" is to lightly rub your thumb across the edge. You
can get a pretty good feel for sharpness. That's crosswise - not lengthwise,
or there'll be blood everywhere!
What you Need & Don't Need
You Need Stones
You 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. 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).
- Medium Stone: This is your workhorse stone for preparing
a new knife or for re-edging your knives if they have become unpleasantly
- Fine Stone: This stone will be used to finish the edge
after using the medium stone. It is also the stone you will do a few
strokes on instead of a sharpening steel every time your knife starts to
feel just a little off its best.
- Superfine Stone: Hard Arkansas and the like are great for
woodworking tools, but just a bit too fine for the kitchen.
- Coarse Stone: Useful for working out nicks and dents in
an abused blade. Hopefully you won't need one of these.
- Sharpening Steel:
The traditional steel is useful for realigning the edges of carbon steel
knives. Contrary to what you may have read, the steel, in its traditional
form, is not a "hone". A hone is a very fine stone that removes metal. The
steel does not remove a significant amount of metal from the blade.
The job of the steel is to return an edge that has become bent to the side
to a straight centered position. It does this through very high pressure,
resulting from the tiny point of contact between the knife edge and the steel.
It works best on soft blades, and I suspect people's insistence on using the
steel is why most European makers tend to make their knife blades a bit on
the soft side.
For modern hard carbon steel blades some knife experts consider the
serrated steels you'll commonly find in the stores ineffective and recommend
a smooth steel. For stainless knives the effectiveness of either type of
steel is subject to considerable doubt.
Because knife users have perceived traditional steels ineffective with
today's knives, many have switched to ceramic or diamond grit steels.
These are hones and do remove material from the blade edge.
My question is simple. If you're going to be using a hone, why not use a
more effective hone, your fine sharpening stone? In my opinion a steel is
of little use today, unless you are making heavy use of traditional
carbon steel knives. The strokes for honing the edge are exactly the same
as sharpening (see below) but just a few strokes on the fine stone.
If you do use a steel, there is controversy there too. Some still use it
in the air, as in the photo above, which makes a good show. Others put it
point down on the cutting board like a giant nail, which gives better
control. Some stroke the knife sharp edge leading (most) and others sharp
edge trailing. Even the recommended angle of knife to steel
differs, though I'd agree with the 22° opinion (for knives edged at
22° and reject steeper angles). All agree the stroke should be
simultaneously across and along the rod, and most agree that 10 strokes on
each side is about right.
Photo © i0007.
- Sharpening "Systems"
There are many
"sharpening systems" on the market. Most of these contraptions are aimed at
holding the knife blade at a consistent and measured angle to the stone. I
haven't time for these. When my knife doesn't feel right I want to just grab
a fine stone and take a few strokes and get back to cutting. Setting up and
taking down a "system" just takes too much time and will discourage me from
sharpening my knives often enough.
Perhaps the back angle will be a little rounded at the shoulders when
sharpening free-hand? Well, it happens that a convex edge is considered
one of the better edge forms, offering good durability. Provided the
back angle is nicely formed and the edge angle is properly sharp, a little
rounding isn't a problem. A lot of rounding is a problem though, so do your
best to hold a correct and constant angle.
If you are simply not confident you can hold angles well, the Lansky
sharpening system (photo) is well thought of, reasonably priced and
relatively quick to set up and take down. It comes in both diamond and
regular stone versions. Photo ©
- Electric Knife Sharpener: One thing
you learn from comparative reviews is that most of these don't work all that
well. Most motorized sharpeners remove too much metal too fast and will wear
out your knives long before their time. Angles are often restricted so you may
not be able to use the ideal angle for the type of knife you are sharpening.
A knife should never be allowed to get so dull it needs an aggressive knife
sharpener. If you get a bad ding in the edge of a knife you can send it
out for professional sharpening, but theoretically that should never happen.
If you do want an electric knife sharpener (commercial kitchens have them
to save time and reduce training costs) the Chef's Choice line is the
run-away favorite. The 2000 model for larger commercial kitchens can be
had for around $430. There are many other models for smaller kitchens going
down to about $60, with declining capability at each drop in cost. Most
who comment like the ones around US $100 or a little more.
How to Sharpen
If 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 Angle
The 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
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
Personally, since I sharpen my knives early and often, I like a shallower
angle and grind the 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
While the same stones and general methods work for both carbon steel and
stainless steel, there is considerable difference between the two.
- Carbon Steel is hard and brittle. It sharpens quickly and easily
to an edge that is actually composed of microscopic teeth. This gives it a
very satisfying cutting feel.
- Stainless Steel is a little softer and a whole lot tougher. It
takes more strokes on the stone to sharpen and the edge will be smoother
and a lot less toothy. It will never have the feel of a carbon steel
knife no matter how sharp. The biggest problem is that during sharpening
it will build up a feather edge that just bends back and forth as you
sharpen from both sides. This must be deliberately broken off.
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.
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