Plaid
vs. Serrated Blades
by Joe Talmadge
I.
Introductions
There's been a jump in recent years in the popularity of serrated
edges, and there's often confusion as to when a serrated edge
is advantageous, versus when a plain edge is advantageous. The
question comes up often in rec.knives.
For
our discussion, we'll need to talk about what we're doing with
the knife. Think about what you can do with a knife: you can shave,
slice, slash, saw, hack, chop, etc. For our purposes, we'll divide
all knife uses into two very broad categories:
Push
cuts: The main cutting is done by pushing the edge through
the thing-to-be-cut. For example, when you shave, you push
the edge of the knife through your beard. When peeling an apple,
you push the edge under the skin of the apple. When chopping wood,
you try to push the edge into and through the wood.
Slicing
cuts: The cutting action is substantially done by dragging
the edge across the thing-to-be-cut. When you slice meat
or a tomato, you drag the edge across the tomato as you cut through
it. Slicing and sawing are examples of slicing cuts.
II.
Plain vs. Serrated: The Conventional View
In general, the plain edge is better than the serrated when the
application involves push cuts. Also, the plain edge is superior
when extreme control, accuracy, and clean cuts are necessary,
regardless of whether or not the job is push cuts or slices.
In
general, the serrated edge will work better than the plain edge
for slicing cuts, especially through hard or tough surfaces, where
the serrations tend to grab and cut the surface easily. Some of
the cutting power of the serrated edge is due to its format alone;
thus, even a dull serrated edge knife will often perform competently
at slicing jobs. The serrated edge gets its slicing ability from
a number of factors. The high points on the serrations will touch
the material first, and this gives those points higher pressure
per area than if the same pressure was applied to a plain blade;
this allows the serration to puncture more easily. In addition,
serrations are normally chisel-ground
into the blade, which means they are thinner (and thus cut better)
than the comparable plain blade.
The
plain edge will work better for applications like shaving, skinning
an apple, skinning a deer. All those applications involve either
mostly push cuts, or the need for extreme control. Serrations
work really well on things like tough rope or wood, where the
serrations bite through quickly.
Generally,
the more push cuts are used, the more necessary it is for the
plain edge to have a "razor polished" edge. A knife edge becomes
more polished when you move to higher and higher grit stones.
Generally, 1200-grit is considered polished; a 6000+ grit Japanese
water stone would polish the edge further.
One
interesting case is cutting a tomato. In theory, you can just
push a blade through a tomato, so a razor polished plain edge
would work fine. However, the tomato is soft, and unless your
plain edge knife is very sharp, the tomato will simply squish
when you start pushing. You can (and many people do) use a slicing
motion with your plain blade, but if it's even a little dull it
won't cut well and it may not even break the skin. Use a sawing
motion with a serrated knife (even a dull one), and your tomato
will slice fine.
You
will read about test after test where the above view is confirmed.
That is, the plain edge excels in push cuts, and the serrated
excels in slicing cuts. This confirms the conventional view ...
to an extent.
III.
Plain vs. Serrated Re-thought
Since
actual tests confirm the truth of the conventional view, what
more is there to be said? The problem is that the tests are often
not as thorough as they need to be. That is, when testing plain
vs. serrated performance, most tests are comparing a plain polished
edge to a serrated edge. Given that, it is no surprise that the
serrated blade easily outperforms the plain blade when cutting
(for example) rope.
A
polished edge is not the only choice with a plain blade. One can
get the plain edge to perform much differently when sharpened
with coarser stone. People who cut rope often use a plain edge
sharpened on a file, to get an incredibly coarse, "micro-serrated"
edge that performs wonderfully at slicing jobs. So the knife testers
are testing with polished plain edges, whereas people experienced
with cutting rope use coarsely-ground plain edges.
Whether
or not serrated blades will out-slice coarse-ground plain blades
seems to depend on the medium being cut. Harder materials (or
materials under tension) do well for serrated blades. With softer
materials, the serrations will sometimes catch and unwind the
material rather than cut -- in this case, coarse-ground plain
blades may easily out-slice serrated blades.
So
the claim that serrated edges work better than plain edges for
slicing needs to be re-examined. It appears that as materials
get harder or put under more tension, the serrated edge may slice
a bit better than a coarse-ground plain edge. As the material
gets softer and looser, the coarse-ground plain edge may slice
a bit better. And as we go towards push cuts, the polished plain
edge comes into its own. The user may want to experiment on those
materials that he often cuts, before choosing the edge format.
In
addition, keep in mind that the coarse plain edge is much easier
to sharpen than the serrated edge. Just grab your file or extra
coarse stone, take a few swipes, and you're ready to go. With
the serrated blade, you'll need to find a sharpening rig with
the special serrated blade sharpener. Balancing this is the fact
that serrated blades need to be sharpened less often.
IV.
What Should I Carry?
Should
you carry a serrated blade or plain blade for everyday utility
carry? Unless you *know* that the majority of work you'll be doing
heavily favors slicing or pushing (e.g., "I spend all my time
whittling"), it may not matter much. My experience has been that
general utility work is usually general enough that either format
works just fine, though these days I tend to lean towards plain
blades. Also keep in mind that by changing your sharpening strategy
on the plain edge, you can significantly change its characteristics.
If you do a lot of push cutting, you want to go with a razor polished
plain edge. If you do a lot of slicing, you'll need to decide
between a coarse-ground plain edge and a serrated edge. I don't
mind sharpening, so I lean towards plain blades, strategically
sharpened to the right grit (polished or coarse) for the jobs
I happen do be doing.
Occasionally,
people mention that the serrated edge looks intimidating to the
masses. This could be good if you're using this knife primarily
for self defense and want an intimidation factor. Or it could
be bad, if you're carrying for utility work and don't want to
scare people (especially the nice officer who pulled you over
for speeding and asks to look at the knife in your sheath). Rumor
has it that airport guards are particularly strict about serrated
edges. Other than at airports, I don't think the menacing appearance
of the serrated edge is important enough either way to affect
what I carry.
V.
Thoughts On The Partially-Serrated Blade
Another
option is the combination plain/serrated edge. This format appears
to have overtaken the all-serrated format. Typically, the 50%-60%
of the blade nearest the tip is plain, while the back 40%-50%
is serrated. There are mixed feelings on this format. Many people
swear by this format, and feel that it is a good compromise, giving
the user the choice of precise push cuts from the plain edge,
and the advantage of the serrated edge for tougher materials.
However, keep in mind that on a 3.25" blade, there's maybe 1.25"
of serrations. The detractors of this format feel that 1.25" is
too short a length for the serrations to be really be useful,
and the length of the plain edge is being sacrificed for no good
gain.
My
own philosophy on partially-serrated blades at the moment is that
since I have both edge formats in one knife, I try to let each
one shine in their respective areas. So I'm razor polishing the
plain edge part, often on a 1200 grit diamond stone or even 6000
grit Japanese water stone, and then stropping it. The plain edge
is scary sharp for push cuts, and I use the serrations when I
need to cut through hard or fibrous material.
Partially-serrated
blades are often serrated at the "wrong" place. For example, for
camp use, I might want the belly serrated for cutting my steak,
and the part near the handle razor-polished for whittling and
control-type usage. However, 99.9% of partially-serrated blades
are ground exactly the opposite: the ripping inaccurate serrations
are at the control part of the blade, and the plain part is out
at the slicing part.
In
theory, one can use a plain blade to get similar performance to
a partially-serrated blade. Just razor polish the plain blade,
and then rough up one part of the edge on a file, to get a knife
that will excel at push cuts at one point of the blade, and excel
at slicing cuts at another.
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