Sharpening FREQUENTLY ASKED QUESTIONS
II. The Fundamentals of Sharpening
- Getting a sharp edge
- What angle?
- What kind of stone?
- Should I use oil or water on my stone?
- How fine should my stone be? Important notes on grits!
- Using a steel
III. Putting it all together
- Freehand tips and tricks
- Why does my knife go dull so fast?
- Putting it all together
IV. Sharpening The "Differently-Ground" Blade
- Those pesky serrated blades
- The Moran (Convex) edge
- The chisel-ground edge
V. Overview of various sharpening systems
- Clamp-on sharpening guides (Razor Edge, Buck, etc.)
- Clamp-and-Rod rigs (Lansky, Frost, etc.)
- V-type sharpeners (Spyderco Triangle, etc.)
- Other miscellaneous
- Freehand sharpening, and its wondrous advantages!
When I started writing this FAQ, I began by writing a detailed
treatise on how to sharpen. I soon found that there was no way I
could do this in the kind of detail I wanted without ending up with a
book-length FAQ. As it turns out, someone has already written a book
on sharpening, and done a better job than I could have done. So the
most important part of this FAQ, for the beginner, is the following
recommendation: the first thing you need to do is buy and read _The
Razor Edge Book of Sharpening_ by John Juranitch. No matter what
sharpening system you end up using, the fundamentals as laid out by
Juranitch remain intact. I don't agree with Juranitch on everything,
but the illustrations he gives really help with understanding the
So this FAQ will discuss the central elements of sharpening, and then
go on to more detailed subjects. Sharpening angles, hones, sharpening
systems, the latest fads in edges (e.g., chisel grinds), etc.
Basically, Juranitch will show you how to get a burr and grind it off
to end up with a sharp knife. Hopefully, the FAQ will tell you
For many people, when they try to sharpen a knife, the knife actually
gets duller! If it's any consolation, I was in the same boat at one
time. The best way to start out is to read about the sharpening
fundamentals, and then use some kind of sharpening system (discussed
below) that pre-sets the angles. That way, you can begin by learning
how to raise a burr, feel for the burr, and then grind it away,
without having to worry about keeping the angle consistent as well.
When you understand how to sharpen, then you can get rid of the rig,
buy some flat hones, and learn how to sharpen freehand.
II. The Fundamentals of Sharpening
- Getting a Sharp Edge
Okay I lied about not discussing the sharpening ritual itself. Here's
a much-too-short review of the sharpening process, before we get into
the rest of the FAQ. If this section is confusing, read _The Razor
Edge Book of Sharpening_. Many of the subjects in this section (e.g.,
stone grits) are explored further elsewhere in the FAQ.
You grind one edge along the stone edge-first until a burr (aka
"wire") is formed on the other side of the edge. You can feel the
burr with your thumb, on the side of the edge opposite the stone. The
presence of the burr means that the steel is thin enough at the top
that it is folding over slightly, because the bevel you've just ground
has reached the edge tip. If you stop before the burr is formed, then
you have not ground all the way to the edge tip, and your knife will
not be as sharp as it should be. The forming of the burr is
critically important -- it is the only way to know for sure that you
have sharpened far enough on that side. Once the burr is formed on
one side, turn the knife over and repeat the process.
To re-cap, you've sharpened one side only until you felt a burr along
the entire length of the opposite side, then you move sides and repeate the process. I suggest you do not follow the directions that
come with many sharpeners, of the form "Do 20 strokes on one side,
then 20 strokes on the other". You go one side only until the burr is
formed; if that takes 10 strokes or 50 strokes, you keep going until
you get a burr, period. Only then do you flip the knife over and do
the other side.
Having raised a burr, our job now is to progress to finer stones, in
order to make the edge smoother and remove the burr. So now we run
the blade along the stone from end to tip, this time alternating sides
with each stroke. Move to a finer stone, and then do it again.
Sometimes, the burr is turned directly downwards during sharpening,
and since it is very thin and razor sharp, it seems like an incredible
edge. This is called a "wire edge". But being fragile, it will break
off the very first time you use the knife, leaving you with an
extremely dull knife. If you seem to be getting good sharpening
results on your knives, but they are getting dull very quickly with
little use, you may be ending up with a wire edge. If that's
the case, you'll need to be careful and watch out specifically for a
wire edge; you should try progressing down to finer stones, try
double-grinding the edge, and give the knife a quick stropping once
you're finished (all these terms are explained below). If your knife
is fading fast as you're sure it's not because you left a wire edge,
steeling between uses may be what you need. My last few strokes on
the stone become progressively lighter, to avoid collapsing the edge
and raising another burr.
On a badly-worn or damaged edge, I'll typically start with a medium
(300-400 grit) stone, then move to a fine (600 grit) stone, and then
sometimes I'll finish on an extra-fine (1200 grit) stone if I want a
more polished edge. However, once my knife is sharp I try tore-sharpen before it gets too worn down. In that case, I can usually
start on the fine stone. But be sure to read the important notes on
grits later in the FAQ.
Lastly, I may use a leather strop on the knife.
On other sharpening systems, the same fundamentals as laid out above
still apply. For example, on a V-type sharpener, I'll start by
sharpening one side only against the right-hand stick until a burr
forms. Then I move to the other stick until a burr forms. Only
after I've raised a burr from both sides will I follow the
manufacturer's directions and alternate from one stick to the other
- What Angle?
The smaller the angle, the sharper your knife will feel. But the
smaller the angle, the less metal that's behind the edge, and thus the
weaker the edge. So your sharpening angle will depend on your usage.
A surgeon's blade will have a very thin, very low-angle edge. Your
axe will have a strong, thick, high-angle edge.
Something like a razor blade will having an angle of around 12-
degrees, and it's chisel-ground so that's 12-degrees total. Utility
knives will have angles anywhere between 15- and 24- degrees (30-48
degrees total). An axe will have something around a 30-degree angle.
For double-ground utility knives, a primary edge of 15-18-degrees,
followed by a secondary grind of 21ish-degrees, works well. Don't be
obsessed with getting the exact right angle; rather, make sure that
at whatever angle you've chosen, concentrate on holding it precisely.
See also the sections on convex edges and chisel-ground edges.
- What Kind of Stone?
Basically, a stone needs to cut metal off the edge. The stones below
do this well, and for most of us our time would be better spent
actually learning how to sharpen than worrying too much about the
minor advantages of one stone vs. another. Get the biggest stones
you can afford and have room for. Big stones make the job much much
The time-honored stone is the arkansas stone. Soft arkansas stones
provide the coarser grits, with harder stones providing finer grits.
Many people use oil on these stones, ostensibly to float the steel
particles and keep them from clogging the stone. John Juranitch has
popularized the notion that oil should absolutely not be used when
sharpening, and indeed results from people using arkansas stones
without oil have been very positive. However, if you have ever used
oil on your arkansas stone, you need to continue using it, or it will
clog. If you never put oil on your arkansas stone, you will never
Synthetic stones are very hard, and won't wear like natural stones (a
natural stone may get a valley scooped out of it over time). They
clean well with detergent-charged steel wool, I use SOS detergent
pads, they clean very very fast and very well. I know you're thinking
that cleaning with steel wool will cause the stone to shear off the
steel wool and fill up the stone even worse! But I assure you that is
not the case, for whatever reason SOS pads clean synthetic stones,
they do not make the stones dirtier. Spyderco and Lansky are some
manufacturers who sell synthetic stones.
Stones with diamond dust embedded in them cut aggressively. You can
remove metal very quickly if you need to, but be careful lest you
remove too much too fast! DMT, Eze-Lap, and Lansky are some
manufacturers who sell diamond-based hones. Some diamond stones have
the problem that the diamond dust wears off quickly, leaving you with
a useless stone. I have experience with the DMT stones, and can say
that they do not have this problem.
Japanese water stones come in some very high grits -- I've seen all
the way up to 8000! These stones are very expensive. The stones sit
in a water bath, and a slush forms on top that helps the final polish.
Don't know any manufacturers, but Bob Engnath and Gorilla & Sons both
sell Japanese water stones.
Both Japanese water stones and natural stones will eventually dish out
in the center with use. To flatten them back out, put some sandpaper
on a flat surface and rub the stone top on it. Wet/dry 400 grit
sandpaper mounted on a table top or glass is reputed to work well.
- Should I Use Water or Oil on My Stone
John Juranitch has popularized the notion that no liquid should be
used on the sharpening stone. Since oil has been used for many years
on stones, this leads to some confusion.
Basically, the purpose of the stone is to rub against the blade and
remove metal. Slippery liquids, like water and especially oil, make
the rubbing slicker, causing less metal to be removed, causing
sharpening to take longer. On top of that, Juranitch claims that as
your edge is being sharpened on the stone, the oil-suspended metal
particles are washing over the edge and dulling it again.
On an arkansas stone, the oil is supposedly needed to float metal
particles away from the stone surface, lest the stone clog and stop
cutting. Some people on this group have used their arkansas stones
without oil or water, and have reported good results. However, if
you've already used oil on your arkansas stone, you'll probably need
to keep using oil forever on it, because an already-oiled stone will
clog up if not kept oiled. If you have a fresh arkansas stone, go
ahead and use it without the oil, and things should be okay.
I've used diamond and synthetic stones without liquid, and they worked
Japanese water stones are the one type of stone that need water. The
stones are designed to work with water, and as you sharpen a small
amount of the stone's material breaks off and forms an abrasive slurry
along the top.
In any case, the bottom line is: use liquid or don't. Using the
liquid will make the sharpening process slower and messier, but if
you insist on using liquid and are willing to spend more time, that's
your call. If you don't have the skill to hold a consistent angle,
it's all moot anyway!
- How Fine Should My Stone Be? Important notes on grits!
The finer the stone, the more polished your edge will become. The
rougher the stone, the more the scratches in the edge function as
"micro-serrations" (see also the serrated vs. plain edge FAQ). Though
the actual ontological status of the micro-serrations is debatable
(Juranitch says there's no such thing, having looked under a
microscope), the serrated effect of the coarser grind is undoubtably
The more polished the edge, the better your edge will work for doing
push-cut applications like shaving, whittling, peeling an apple,
skinning a deer. Also, your cut will be more clean and precise with
the polished edge.
A rougher, more micro-serrated edge will work better for slicing-type
applications like cutting through coarse rope, wood, etc. The
serrations present more edge surface area, and tend to "bite" into the
thing being cut.
It is possible to get an edge that will shave hair with a medium
(300-400 grit) stone, with practice [I specifically mention stone
grits because many manufacturers call the 300-400 grit stones "coarse"
rather than "medium"]. The medium stone will have pretty big
micro-serrations. In previous version of the FAQ I stated that I find
this too rough a finish for my general utility edge. However, I've
since found this to be a really nice edge finish for utility work --
it won't shave great, but it does a really nice job on cutting coarse
Anyone should be able to get an edge that shaves hair easily with a
fine (600 grit) stone. I find this to be a pretty useful finishing
stone, leaving enough micro-serrations for general utility work but
still being hair-shaving sharp.
An extra fine stone (1200 grit) should start polishing the edge, and
you should end up with a hair-popping sharp edge. This is also a good
choice for a general utility finish, especially on a
partially-serrated blade, where the serrations can be used when the
slightly-polished main part of the blade becomes less effective.
One can buy Japanese water stones with grits up to 8000, which leaves
a polished edge that's so sharp, your hairs will jump off your arm
when they see the edge coming. I would question this finish on an
everyday utility knife which might be called upon to cut through a
thick rope or what have you, but it is a finish that works well when a
polished edge is called for.
************* IMPORTANT TIP ****************
Many treatises on sharpening tend to focus on getting a polished,
razor-like edge. This is partially the fault of the tests we use to
see how good our sharpening skills are. Shaving hair off your arm, or
cutting a thin slice out of a hanging piece of newpaper, both favor a
razor polished edge. An edge ground with a coarser grit won't feel as
sharp, but will outperform the razor polished edge on slicing type
cuts, sometimes significantly. If most of your work involves slicing
cuts (cutting rope, etc.) you should strongly consider backing off to
the coarser stones, or even a file. This may be one of the most
important decisions you make -- probably more important than finding
the perfect sharpening system!
Recently, Mike Swaim (a contributor to rec.knives) has been running
and documenting a number of knife tests. Mike's tests indicate that
for certain uses, a coarse-ground blade will significantly outperform
a razor polished blade. In fact, a razor polished blade which does
extremely poor in Mike's tests will sometimes perform with the very
best knives when re-sharpened using a coarser grind. Mike's coarse
grind was done on a file, so it is very coarse, but he's since begun
favoring very coarse stones over files.
The tests seem to indicate that you should think carefully about your
grit strategy. If you know you have one particular usage that you do
often, it's worth a few minutes of your time to test out whether or
not a dull-feeling 300-grit sharpened knife will outperform your
razor-edged 1200-grit sharpened knife. The 300-grit knife may not
shave hair well, but if you need it to cut rope, it may be just the
If you ever hear the suggestion that your knife may be "too sharp",
moving to a coarser grit is what is being suggested. A "too sharp" --
or more accurately, "too finely polished" -- edge may shave hair well,
but not do your particular job well. Even with a coarse grit, your
knife needs to be sharp, in the sense that the edge bevels need to meet
Stropping consists of running the edge along a piece of leather
charged with some kind of abrasive like stropping paste or green
chromium oxide (I had previously said jeweler's rouge is okay, but
have since heard that a more aggressive cutter is needed). It is done
for a short time to finish off the burr, or for a long time to give
the edge a final polish. Stropping is an easy-to-use finishing step
(as opposed to the difficulty in keeping a consistent angle on a
Before you strop, remember to wash and dry your newly-sharpened knife.
If you don't, you might grind leftover metal particles into the strop
itself. If you need to charge your strop, put a little paste on your
fingers and rub it into the leather.
To strop, you run the edge along the leather with the blade positioned
spine first and the edge trailing (opposite way from sharpening on a
stone). With a thin straight razor, the spine of the razor is always
kept on the strop, and direction is reversed by flipping the razor
over along its spine. In my experience, this isn't necessary with a
utility knife. You can strop with the blade spine raised above the
leather (don't lift too high -- if the edge bites into the leather,
that's too high), and change directions by lifting the entire knife
up, turning it over, and placing it back down.
If you've never stropped your knife before, give it a try. It will
come out very sharp, but of course polished and so optimized for
push-type shaving cuts. The strop to some extent can make up for
less-than-perfect sharpening technique -- a sharp knife can be made
extra sharp on the easy-to-use strop. However, I always tell people
that they should be able to get their knife scary sharp without the
strop; don't let the strop keep you from recognizing weaknesses and
improving your technique on the hone!
In the absence of a strop (say, out in the field), many people use
their jeans and then their palm as a strop. There's probably no need
to point out the danger in this practice, so don't do it. That said,
I must admit to having done this myself on numerous occasions, and
having gotten good results.
A safer and more effective trick is to use cardboard (say, the
cardboard back of a standard notepad). You can optionally charge the
cardboard with metal polish, just rub it in with your fingers. Then
strop as above. Even without the polish, the cardboard will strop
acceptably. Stropping with cardboard has become a de-facto standard
last step for sharpening chisel-ground (single-side ground) knives
these days, for burr removal purposes.
- Using a Steel
The sharpening steel should be an important part of your knife
maintenance strategy, and is maybe the most mis-understood part.
When you use a knife for a while, especially a knife with a soft, thin
edge like that found on a kitchen knife, the edge tends to turn a bit
and come out of alignment. Note that the edge is still reasonably
sharp, but it won't feel or act very sharp because the edge may not
point straight down anymore! At this point, many people sharpen their
knives, but sharpening is not necessary and of course decreases the
life of the knife as you sharpen the knife away. It's also akin to
putting in a thumbtack with a sledgehammer.
The steel is used to re-align the edge on the knife. Read that last
sentence again. Re-aligning the edge is all the steel needs to do.
It does not need to remove any metal. Since the steel's only function
is to re-align, the sharpening steel can be perfectly smooth and still
do its job. You'll see many bumpy steels on the market, but this is
almost certainly because consumers think that steels must have bumps
to work. The bumps can actually mess up the edge, and make the work
of steeling more difficult.
There are two schools of thought on steels. Some people use grooved
steels, which align the edge more aggressively but are harder on the
edge. I use a smooth steel, which is easy on the edge but may align
the edge more slowly.
To use the steel, run the knife along the steel on one side using
light pressure -- no more pressure than the actual weight of the knife
is required! Then move to the other side and do it again. Repeat a
number of times until your edge feels sharp and nice again. I hold the
steel in my left hand, the blade in my right, and lightly run the
blade along the steel while keeping the steel stationary, but it's
perfectly fine to move both steel and knife past each other at the
same time, or whatever works for you.
Most people run the knife down the steel edge first, the same
direction you use when sharpening. This yields good results.
However, theoretically going edge-first along the steel could bite
into the edge while straigtening it, and so many people like to go
spine-first (like when stropping) instead. This method also works
well, and I personally have begun to feel that steeling in this
direction gets my edge the tiniest bit sharper. It is more awkward
to go spine-first, so if you have any trouble with it move to
edge-first, and your edge will end up just fine.
If you steel your knife every time you use it, you will significantly
lengthen the time between sharpenings. I've found steeling to be
critical on kitchen knives, but it's an incredible help even on
III. Putting it all together
- Some tips and tricks
If you want to determine if you are sharpening at the same angle that
the blade already has, try this easy trick. Mark the edge bevel with
a magic marker. Then go ahead and do a stroke or two on the stone (or
take a stroke with your Lansky, or whatever). Now pick the knife up
and look at the edge. If you have matched the edge angle exactly, the
magic marker will be scraped off along the entire edge bevel. If your
angle is too high, only the marker near the very very tip will be
gone. If your angle is too low, only the marker near where the edge
bevel meets the primary bevel will be gone.
Another trick is to use light and shadow to get the edge precisely.
Using strong directly light, lay the edge down on the stone and watch
the shadow below. As you tilt the spine up, the edge contacts more of
the stone and the shadow disappears. As the shadow just disappears
and the edge just touches the stone, that's your angle. If you go
higher than that, you should be able to see the edge tilting over onto
One trick to freehand sharpening is to use your thumb as a guide.
I'll place the spine of the blade against my thumb pad, and rest my
thumb on the stone. That way, I can feel the angle between the knife
and stone, and make sure that it is consistent. Typically, the
hardest part to freehand sharpen is the curving belly of the blade, as
keeping a consistent angle here is more difficult.
I use all these tricks extensively when sharpening freehand, and use
the marker trick even when I'm using a sharpening rig.
One thing to keep in mind is that there's no reason you need to keep
the factory edge. If you're happy with that edge, great. However,
many factory edges are too thick to really cut well. If you're
unhappy with the cutting ability of your knife, don't be afraid to try
lowering the angle a bit.
- Why does my knife go dull so fast?
A frequent complaint I hear is, "I sharpened my knife and did a good
job, it was really sharp. But then after just a few uses it went
dull." Why does this happen?
One of the following factors -- and many times a combination of those
factors -- is at play:
1. Wire edge
If the burr is not properly ground off, but is instead turned
downwards, your knife will feel razor sharp. However, the burr
quickly turns or snaps off, leaving you with a very dull-feeling
knife. Be sure to use a light touch at the end of the
sharpening process and make sure the burr is gone.
2. Thin, weak edge
If the bevel angle you chose for your knife is too thin for
your usage, the edge can chip and get really wavy. Try using
a larger edge angle, or at least double-grinding the edge.
3. Edge turning
In regular use, all edges turn to some extent. If your edge is
much too thin, it will be damaged as above in #2. If it's only
slightly too thin, it will quickly turn out. As long as the
the edge is not being damaged, but simply turning, you don't
necessarily need to re-grind a thicker edge. Instead, see if
frequent steeling will give you the performance you need, it can
really work wonders. Keep in mind it's difficult to see a
turned-out edge by eyeball -- only using the steel will tell you
conclusively if this is your problem.
4. Thick edge
A thin edge will feel sharper than a thick edge. If your edge
is too thick, when it starts to dull even the slightest bit it
may no longer feel so sharp anymore. Consider using a lower
angle and seeing if that helps. Of course, your thinner edge
will be more fragile than the thicker edge, so you may end
up chipping the edge out, and the thinner edge may not be
feasible. I personally feel that this is rarely the real
problem, so be sure to try the other solutions first.
5. Soft steel
Occasionally, a manufacturer or maker will make a mistake while
heat treating, and the steel in the blade will end up too soft.
No matter how well you sharpen, your blade will still go dull
quickly. Often, soft steel is the first thing people point at
when their edges dull quicker than expected. But this problem
really is relatively rare; in the vast majority of cases, it is
one of the above reasons rather than soft steel that's the
problem. So if your edge dulls too fast, don't blame the
steel until you've exhausted the above options. If it's still
dulling quickly, contact the manufacturer, they are often
interested in testing to see if they made a mistake.
- Putting it all together
As you use your knives, you may see your sharpening strategies change.
Many of us seem to be homing in on the philosophy that you should
choose the thinnest, coarsest edge possible that can do your job
without the edge being damaged, especially in the context of general
Thin blades and low-angle edges seem to cut better than thick ones.
They slide through the material being cut with less effort. Which
makes sense -- the wider the V that your edge forms, the more metal
you're pushing into the material. However, go too thin and your edge
can chip out. So go as thin as you can without damaging your edge,
and use a steel often to touch it up. Obviously, what "thin" means
depends on usage. "Thin" means one thing when the job is slicing soft
materials, something else entirely when chopping hard materials.
Lightly double-grinding a shallower bevel on a thin edge may help give
you the best of both worlds. If your first bevel is a thin 15-degrees
(say), try doing a few light finishing strokes at a stouter
Coarser edges slice better than polished ones, but a polished edge
will laterally push-cut (e.g., shave) better. If you find yourself
doing a lot of lateral push cuts, then you'll obviously want to polish
your edge more. However, most people do much more slicing than push
cutting, and as a result end up with a much more polished edge than
optimal. You should play around with coarser grits. The edge won't
do as well shaving hair, but unless this particular knife is a razor
blade, who cares? You may find the knife cutting through other
materials much better than usual.
Lastly, I have become something of a steel fanatic. Steeling your
knife frequently -- even if the blade is of really high-hardness steel
-- works wonders on the edge. It also allows you to have a slightly
thinner (and hence better-cutting) edge, because if you steel
frequently you'll keep the edge aligned. If you don't steel at all,
you'll have to use an edge that's thick enough not to turn, and that
may negatively affect sharpness and cutting power. Remember to steel
frequently, because if your edge's shape gets too bad, the steel won't
work and you'll have to go back and sharpen.
IV. Sharpening The "Differently-Ground" Blade
- Those Pesky Serrated Blades
It is not that difficult to sharpen the Spyderco-type serrations, or
the typical serrations on a bread knife. Both the Lansky rig and
Spyderco's Triangle-Angle Sharpmaker have special hones meant to
sharpen serrated blades. A triangle-shaped hone rides along the
grooves. Although I can't quite get my serrated knives as sharp as
they come from Spyderco's factory, I do get them extremely sharp, and
am satisfied with the results. Don't let fear of sharpening scare you
away from serrated blades.