Submitted by Stuart Smith, well known South African bladesmith.
I have come to notice many people’s ideas on the concept of a sharp
knife. What follows are my accounts and opinions and are not to be taken as
gospel on what sharp is. Too many times I have seen a customer pick up a
knife on my table, grasp the knife edge up and run his thumb sideways across
the blade and claim that it is or isn’t sharp. Let me ask you this question
as makers and users of knives, when last did you cut sideways with a knife?
How can a judgment of sharpness be made with this test? Through reading
various articles on sharpening knives I have learned several interesting
facts on the nature of sharpness.
Sharp is not what we think it is. Most knife makers are aware that a blade
of any sharpness consists not of a smooth edge but of micro teeth which when
carefully honed merely become smaller micro teeth. When the “knowledgeable”
customer does the PT (perpendicular thumb) test and feels course teeth, in
his mind, the blade feels sharp. But just you try to shave with a blade like
that. When the PT test is done on a blade with a truer hone he claims it is
blunt because there is no bite due to coarser teeth. Please do not mistake
me for saying that you can’t feel the sharpness this way. The key ingredient
is knowledge of what constitutes sharp and “false sharp”.
Better tests include running the blade along a finger nail to see if it
bites. Blunter spots can be felt when the cut goes smooth or slides off the
nail. You can also shave arm hair with it but there is usually only a
limited supply of that. If you are ambidextrous you can shave with your left
hand. I did it once and ended up cutting myself. A paper slice is a good
test however the test itself tends to make the blade blunt. The perfect test
of true sharpness is to slice a loose piece of newspaper with out tearing
it. This is a near impossible test unless your blade it ultra sharp.
When larger micro teeth are present a blade relies on its edge geometry to
complete the task of cutting. The teeth only break the surface of a
particular job and the rest of the knife follows through. This can require a
larger cutting motion with several passes which will wear the teeth down
making the knife blunter. In turn the user will then sharpen it the same way
to cause the same problem. Many of you will notice when you go to a carvery
that the chef keeps sharpening the knife on a sharpening steel, over and
over again. Now smaller micro teeth will break the surface easier requiring
fewer strokes to finish a job, thus wearing them down less. Anyone who has
used a truly sharp knife will never have it any other way. The blade almost
feels like it glides through its work.
There are of course other factors contributing to the sharpness of knives.
The purpose of the knife is also crucial. Its purpose dictates its edge
geometry or the kind of bevel the maker will apply. A fine caper/skinner
will have a fine edge with a fine bevel, whereas a camping knife will have a
more robust bevel for heavier use. These factors however, should not affect
how sharp it “should” be. Just because it is a camp knife doesn’t mean it
should be like the garden axe (which by the way, the one in my garden is
razor sharp). Many who have seen and participated in the Hammer Inn cutting
competitions can attest that a razor edge definitely has an advantage in
performance. The idea is that, however impractical it is to do so, one
should be able to skin with a camp knife as easy as chop wood.
I am reminded of a humorous story that the Harvey's told me. They once made
a belt knife for a customer, and upon receipt of the blade he expressed
great satisfaction. A little while after he had acquired his new blade the
Harvey's received a phone call from him. The distraught customer had just
cut himself. When I say a short while, I mean a couple of hours. He
complained that the knife was too sharp!! Heavin politely apologized and
suggested that he be more careful. A little while later he phoned again!
Much upset and in great anguish he complained again. “Your knife is too
sharp!” To which Heavin replied “Would you like us to make you a belt
spoon?” An answer which I personally use to this day when people say my
knives are too sharp. Needless to say the customer ceased cutting himself or
stopped calling. We may never know.
The moral of this story, I feel is quite simple. A sharp knife will cut.
This crude observation is what knife making is all about. Why make a knife
if it is not going to be sharp. Believe it or not, a blunt knife is more
dangerous than a sharp one because it will not do the job it is intended
for.
I was very impressed with the quality of work at the Guild Show. Thanks to
Melinda for a great event. I saw knives that boggle the senses and made me
weep with admiration and envy. However I was shocked to find that several
makers’ knives were only “sharpish”. Now I do not claim to make knives
better than Guild members but I must say this. I was taught that how a knife
cuts comes before how a knife looks. Some makers say that they won’t make it
too sharp for fear that someone might cut themselves. That’s why we attend
the table to remind the customer that we don’t, in fact, sell spoons. We
cannot however keep an eye on the customer all the times.
I learned this the hard way when two gents were looking at a knife. I warned
them to be careful because the knife was “Razor Sharp”. My exact words.
Never the less, one was holding the knife tip up and blade out. He turned to
the other gent to show him the knife. He turned bodily and proceeded to
slice a gash about 80mm long and about 20mm deep in the mans arm. When he
saw it he quickly put a handkerchief on it and claimed he was fine and
walked away. I know he needed stitches. The amazing part was that he didn’t
know he was cut until I pointed it out. It was as clean and neat as a
surgeon’s incision. Impressed and shocked I carried on with my day.
For this reason I may accept that some makers are nervous about selling
knives that are sharp to such a degree. But we must ask ourselves as makers,
will it impress the customer more if he has to sharpen the knife before he
uses it the first time, or if it is ready and ripping straight off the
table. The problem is that sometimes the user cannot get it quite as sharp
as we can, sometimes even making the blade blunter as he tries to sharpen
it. We must realize that a lot of users out there are relying on a
sharpening system that may not even work on some of the custom steels we
use. Recently I had to sharpen another maker’s knife because it was too hard
for the customer to sharpen with conventional methods. If makers sold knives
proper sharp to begin with, these kinds of things could be avoided. I pride
myself on extremely sharp knives and believe that all makers should feel the
same. Hell, even Bertie Rietvelt’s art daggers have a razors edge and who’s
going to use one of them on a slice of biltong. Some might say, “Yes. But
how long will the edge last?” That is up to the maker, the steel and the
heat treating methods he (or she. Sorry Heather) uses.
In conclusion, we should stress to our customers that knives are meant to be
sharp and this is what they should come to expect from a custom made knife.
We have standards to uphold not only in visual quality but in performance as
well. If your reason for lack of sharpness is because you struggle to get it
that way, there are an abundance of makers who will gladly help you gain a
keen eye for a keen edge.
