Hone an incredibly sharp edge with a $35 combo stone.
By Tom Caspar
For this woodworker, it doesn’t get any better
than using a sharp hand tool. Not just
kind of sharp, the way new tools come out
of the box. I mean really, really sharp, with an
edge honed to perfection by a well-maintained set
of sharpening stones. In search of that perfect
edge, I’ve tried oil stones, diamond plates and
sandpaper. With enough time, money or elbow
grease, all these materials can deliver top-notch
results. But none can beat waterstones, which
combine fast cutting, easy maintenance and great
value in one package.
Types of stones
Waterstones were first quarried from small mines in
Japan more than 1,200 years ago. Today, most waterstones
are made in a factory. They’re composed of aluminum
oxide, silicon carbide or chromium oxide abrasives heated
at high temperature to fuse into a brick-shaped porous
matrix. Many hold water just like a sponge.
Most waterstones come in two sizes: regular and large.
Large stones are thicker, wider and longer, so they have
more wear surface. The extra width of a large stone is
handy for wide plane irons, but not essential.
Single-grit stones are my first choice,
because they have four working surfaces.
I use the top and bottom for plane irons
and the edges for chisels. The wider the
edge, the easier it is to balance the stone.
Click any image to view a larger version.
Combination stones are the best value,
because you get two grits for the price of
one. However, the stone has only one
working surface for each grit. Many different
grit combinations are available.
Ceramic stones are a special type of
waterstone.They’re more expensive than
ordinary waterstones, but save time
sharpening. They cut faster and wear
more slowly than other waterstones.
Quarried stones are the way to go if you
use high-grade Japanese tools. They produce
a softer-looking finish than manufactured
stones do. Traditional artisans
believe that’s better for examining the
edge of Japanese laminated steel.
The least-expensive way to get a decent edge is to
buy a regular-size combination stone. Go for a
1,000/6,000 coarse/fine, which runs about $35 (see
Sources, page 36). A large stone costs another
$15 to $20 and requires reflattening less often.
A 1,200/8,000 medium/fine stone, which costs
about $45, gives you a slightly sharper edge, but
requires more strokes on the medium side to prepare
a very dull edge for final polishing.
I use a three-stone system of large single-grit stones:
800 coarse, 1,200 medium and either 6,000 or 8,000
fine. Compared with using the two sides of a combination
stone, this set requires fewer strokes on each
grit. That produces less wear, so keeping the stones
flat is much easier. Buying this set of three adds up to
$80 or more, but considering the dough I’ve spent on
good hand tools, it’s worth it. After all, your hand tools
are only as good as the stones you sharpen with.
If your tools have very high-quality blades, such as
A2 or cryogenically treated plane blades, super-fine
stones with 12,000 or higher grit will produce an
unbelievably sharp edge. They cost from $100 to
$400 (see Sources, below). These stones don’t help
very much, though, on average-quality tools, whose
steel won’t hold a supersharp
edge for more than
a few licks.
All manufactured waterstones
are graded by grit numbers. The
higher the number, the finer the
grit. Roughly speaking, grits fall
into five functional categories. In
general, the higher the grit number,
the higher the price. Within
one grit category, higher-priced
stones cut faster and resist
Check the directions that come with your stone; some types
don’t require presoaking, and others should not be soaked or
Most coarse and medium waterstones, though, should be
immersed in water when not in use. This keeps them saturated
so the surface doesn’t dry out quickly when you’re sharpening.
If you’ve just bought a new stone, soak it overnight before
trying it out. Fine and super-fine stones don’t absolutely require
soaking, but if you do soak them, they’ll be ready to go right away.
I keep my stones in a plastic tub with a lid. They’ve been soaking
since 1979! I add a drop or two of bleach to keep the water free
of green scum.
Use lots of water
Flood the top of a waterstone with water when you sharpen. This suspends
the small particles of worn-off steel in the water, keeping the particles from
clogging the stone’s surface. You can use a cup or spray bottle or simply
dip your fingers in a water container to continually keep the stone
wet. I use a plastic mustard bottle.
The undeniable downside to waterstones is that they’re
messy—though not as messy as oil stones. Your hands will get wet
and grubby. To protect my bench, I place my stones on a cookie
sheet. Open-weave shelf liner below the stones and under the cookie
sheet keeps everything from slipping. After sharpening, I dry my tools
right away so they don’t rust, place the stones back in the storage tub and
wash my hands. The gunk comes off quite easily with ordinary soap.
Keep 'em flat
Routinely rub your waterstones with 220-grit wet-dry
sandpaper placed on ordinary plate glass that’s 1/4 in. or
more thick. A waterstone cuts fast because its surface
wears down quickly, constantly exposing new, sharp abrasive
particles. This wear eventually creates an uneven surface,
which produces an undesirable curved edge on
chisels and plane irons.
Make a squiggle line with a pencil down the
length of a stone before you flatten it. Put a little
water on the plate glass so the sandpaper
sticks. Then put lots of water on the paper and
go at it. When the pencil line is gone, the stone
is flat. I also sand a 45-degree bevel on every edge
of the stone to prevent flaking.
With my three-stone single-grit system, I skip the
sandpaper and glass method and simply flatten all
three stones against each other. The trick to avoid making
concave and convex pairs is to continually alternate
sides. Rubbing medium against fine does no harm to the
fine stone. This is so easy that I flatten my stones before
each sharpening session. It only takes a minute or so.
Flattening the sides removes the inked grit numbers, so I
write them in pencil on the end of each stone.
Flatten a combination
waterstone with wet-dry
sandpaper on glass.
Flatten single-grit stones by
rubbing them against each
other. Both wear down until
they mate perfectly flat.
Make a slurry
The secret to sharpening on a finegrit
stone is to build up a paste slurry
before you get going. It looks like thin mud. A
slurry keeps the microscopic metal particles removed
from the tool’s edge in suspension more effectively
than water alone. That makes sharpening go faster and
results in a better edge. The paste also makes the stone
more slippery, which prevents the backs of your chisels
and plane irons from sticking to the stone’s surface.
You can get by without the slurry, but sharpening will
be more difficult.
To create the paste, wet the stone and vigorously rub
its top with a Nagura stone, which costs $10 to $20. The
Nagura wears away the stone to leave a chalky paste. As
you sharpen, the paste will be pushed to the ends of
the stone. When that happens, wet your fingers and
work the paste back over the whole stone, or rub the
stone with the Nagura again. When you’re done, leave
the paste to dry on the stone, ready for next time.
Guides are OK
Some folks claim
that the wheel underneath
a honing guide will quickly hollow out and ruin
a stone’s surface, but I disagree. You just need to use
the right technique. I concentrate my finger pressure
on the edge of the tool, not on the honing guide
itself. The harder you press on the tool’s edge, the
faster the stone will cut, but there’s no reason to bear
down on the wheel.
(Note: Product availability and costs are subject to change since original publication date.)
The Japan Woodworker, japanwoodworker.com, 800-537-7820, More than 40 waterstones available.
Sharpening Systems, shaptonstones.com, 877-692-3624, Ceramic stones with 120 to 30,000 grit, $53 to $130.
This story originally appeared in American Woodworker September 2005, issue #116.
September 2005, issue #116
Purchase this back issue.