The importance of having a sharp knife is well known to those who have ever used one. Reeds that have been scraped with a sharp knife seem to vibrate differently than those that have been scraped with a dull one. Reeds scraped with the former tend to respond more easily and with a less buzzy sound than those scraped with the latter. Sounds ideal, but what's the reason? One theory I've heard is that a sharp knife tends to LIFT OFF the fibers using almost no downward pressure. A dull knife requires downward pressure on the cane. In so doing, it not only rips the fibers,

but compresses them, causing resistance to vibration. If this theory is correct, the scraping of a reed with a dull knife is at cross-purposes with itself. One scrapes a reed (usually) to remove resistance to vibration, but the act of scraping simultaneously adds resistance by compressing the fibers. Obviously, this is not very efficient; worse, by the time the reed becomes easy enough to play (Hercules notwithstanding) it tends to be somewhat buzzy, due to unnecessarily thin cane.

Anyone who doubts that a sharp knife will change sound quality is encouraged to try to finish a reed with a dull knife, and then to make several scrapes with a sharp one. The difference may astound you.

In addition, you may find it much easier to scrape the tip of the reed with a sharp knife than a dull one. Because almost no downward pressure is needed, it is possible to remove cane well beyond the point that a dull knife might have ripped the tip off.

Another advantage is that it is possible to scrape in very selective places. "Fine-tuning" the sound becomes easier.

The last obvious advantage is that reed making takes less time. A sharp knife will cut faster than a dull one. Ask any chef in a Japanese restaurant.

How sharp is sharp? A sharp knife will sink into your fingernail upon contact -- USING NO PRESSURE WHATEVER. The weight of the blade (even a small blade) should be sufficient to make it stick in your fingernail. It should also be able to easily shave the hair on your arm.

Ideally, I want my knife to be able to remove cane simply by touching it with a subsequent flick of the wrist. In my opinion, if a knife doesn't do that, it's not sharp.

If this sounds intimidating, let me assure you that it is not. In fact, it is not even particularly difficult to achieve, if you learn some guidelines.

Basically, knife sharpening is manipulating a burr. A burr is produced when you cut, grind or rip a piece of metal. It's that which sticks out in one or many directions from the body of metal itself. It can be EXTREMELY sharp. It can also be dull. Skillful manipulation enables the control of both direction and sharpness of the burr.

In my opinion, the best, most effective manipulation of the burr is as follows (in relation to the ultimate cutting direction):

1.) get the burr going "backwards"

2.) get the burr going "forwards"

3.) shear the burr

NOTE: It is necessary to have the burr going ALL in one direction. This will eventually put all of the sharpness on the side you're using, and not on the unused side. What does this mean? Let me illustrate.

Note that the very end of the knife steps in on both sides due to sharpening NOT FLAT on the stone. This is necessary for this sharpening technique. One will notice from the drawings that the burr is a continuation of the angle of one side at the point of the knife. Thus, if, while sharpening, there is a burr emerging on one side of the blade, this tells us that the other side has reached the point of the blade. Right?

First, the knife should be sharpened so that the burr is on the "wrong" side. Pull the knife towards you, edge first.

Do this until you can feel (with your fingertips) the burr emerging from the ENTIRE LENGTH OF THE BLADE (the burr will be on the side that did NOT touch the sharpening stone).

Second, turn the knife over and draw it across the stone (away from you) until the burr begins to emerge on the opposite side, THE ENTIRE LENGTH OF THE BLADE.

NOTE: the angles should be approximately 10 degrees on the first side, 45 degrees on the second side. DO NOT INCREASE THE ANGLE AS YOU SHARPEN. The knife will sharpen more

easily for a longer period of time if the angles are not too steep. Be a little patient and maintain the angles until the burr emerges. This is important.

When you have completed step 2, the knife is potentially sharp. All that remains is refinement of the burr. It may, at this point, feel terribly dull. Never fear. There are actually two reasons why a knife would feel dull. The first and most obvious is that there is no point on the edge, that is to say, no sharp angle. The edge is rounded.

The second reason is that there is a burr, and it is too big. As I said before, a burr can be extremely sharp and can also be very dull. This is because a burr, usually fairly thin metal, bends easily. The longer the burr, the more chance there is that the burr will bend, or is already bent. A burr like the one shown would not cut anything. If we were, however,

to shear off the bent part, we would find that it is indeed sharp.

Anyone who has ever gotten a paper cut will attest to the inherent sharpness of something which, in other circumstances, can feel dull.

Refinement of the burr is achieved by simple repetition of steps 1 and 2. At this point, it is no longer necessary to get the burr completely going in the "wrong" direction (step 1). Be sure, however, that step 2 is right on the mark. This is the side you will be using to scrape with. As the burr gets smaller, repeat the process on the next finer stone. I use a Norton Crystalon combination to start (both sides if needed). I then use a Norton Medium and Fine India stone. I finish with a hard Arkansas stone. By the time you reach the finest sharpening stone, the knife should be very sharp. Frighteningly sharp, in fact.

When using the two finest stones, there is an additional step which further refines the burr. This is STEP 3. Lay the knife flat on the stone in the "wrong" direction (step 1).

Push and pull the knife in a direction perpendicular to the sharpening stone. This sheers the burr and tends to compress the now microscopic points of the burr. Very little pressure is needed. Those points are very small.

To review, the three motions are:

1.)"Backwards" at a slight angle to the stone. TOWARDS you.

2.)"Forwards" at a slightly greater angle to the stone. AWAY from you.

3.) "Backwards" flat on the stone -perpendicular to the stone. UP/DOWN. The burr is manipulated thusly:

DO NOT grind your knife in a circular, figure 8 or any other creative pattern on the stone. It is most important to maintain an exact angle between knife and stone. The easiest way to accomplish this is one straight pass. Also, always start with the handle close to the stone and draw it away so that the end of the knife comes off the side of the stone. It is best not to have the knife stop on the stone.

When the knife has been newly sharpened, sometimes the burr is a little too big and unwieldy and may not become sharp "first time - every time." When this occurs, simply repeat the process on the finest sharpening stone. It should get sharp after one or two more tries (the whole process takes only about ten seconds). The burr should become smaller, more predictable and easily manipulated.

Once again, DO NOT INCREASE THE ANGLE OF THE KNIFE TO THE STONE as time goes on. If the burr gets so small that it no longer feels sharp, simply return the knife to the next coarser stone and repeat the 3-step process until a small burr emerges. You are then ready to start again. You can go on for a long time (years) this way. Also, maintaining the same angles religiously makes it easier to remember the angles you use. Eventually your hand will automatically find the correct angle almost every time.

There is one pivotal bit of information that needs to be discussed at this time. It is very important, as the success of one's knife sharpening depends upon its mastery. It involves the ability to control the burr at the very edge of the blade. To control this burr, it is necessary to be able to "feel" the angle of the knife on the stone. What does this mean? Certainly it would be difficult to feel the tiny bevel at the point of the knife. It's probably only a tenth of a millimeter long! It is true that simply placing the knife STATICALLY on the stone and expecting to feel the point would be no small accomplishment. However, DYNAMICALLY it is not very hard to feel this. When the knife is moving ever so slightly forward

(while also putting a good amount of pressure downwards), its motion will stop when the angle of the knife is such that the edge point touches the stone. This is important. Re-read the last sentence.

Thus, once the initial angles are put on the knife, the honing process begins by placing the knife on the stone at an angle slightly smaller than optimum. If you're not sure where optimum is, start the knife flat to the stone. Now, slowly increase the angle while pressing down and (slightly) forward. WHEN THE KNIFE STOPS, YOU HAVE REACHED THE EDGEPOINT OF THE KNIFE. Hold the knife at that angle -no more than that, please - maintain downward pressure and draw the knife across the stone. In all probability, that will reverse the burr. If not, or if only partially, repeat the process. MAKE SURE THE KNIFE STOPS EVERY TIME BEFORE DRAWING IT ACROSS. Periodically check the burr and see what it's doing. (See "three ways to check the burr.")

That, in a nutshell, is how to sharpen a knife probably better than you ever have before. In the past year I have had NO problems producing an extremely sharp edge on my knife. (Actually, I'm even a little surprised at that.) I have given master classes and lessons in knife sharpening. I have sharpened many peoples' knives. With rare exceptions, only when old knives were just too far gone to spend the time on, I have had 100% success with this method. This process works with heavy razor knives, beveled knives, wedge knives; it makes no difference.

As long as the steel is hard enough to maintain a fine edge without crumbling, knife sharpening is actually - dare I say it easy! Left-handed people should simply reverse the instructions.

Any questions pertaining to this sharpening process or to knives in general may be directed to:

Michael Rosenberg
c/o Shepherd School of Music
Rice University
Houston, Texas 77001
(713) 527-8101, ext. 3714

THREE WAYS TO CHECK THE BURR

For large burrs:

1 ) With the fingertips.

2) Run your fingernail down the side of the knife and feel for a "click" at the edge.

For small burrs:

3) Touch the edge of the knife to the fingernail. Move in one direction and then the other (backwards and forwards). This will tell you in which direction the burr is pointing, and also how sharp it is.

COPYRIGHT 1980 by MICHAEL ROSENBERG

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