How to Sharpen a Paring Knife
Posted on January 4, 2010
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A sharpening stone or oil stone is a tool used for maintaining and knife blades. It consists of a carborundum stone, a block of ceramic, or a metal plate with embedded diamond dust and there are generally three grades of stones, coarse for rapid renewal of a badly damaged blade, medium stone for general work, and fine or Arkansas stone to put the final edge to the blade.
When sharpening, most of these stones require a lubricant, such as oil or water, to carry away the cuttings from the paring knife’s edge. The lubricant prevents the pores in the stone from getting clogged up with the metal and grit.
Professional chefs use honing steel to maintain the edge on a knife rather than for intensive sharpening. Honing steel is often mislabeled as sharpening steel, but they don’t actually sharpen unless they are comprised of fine diamond grains. Honing steel was originally used to straighten the sharpened edge of a blade where repeated use had eventually pushed it to one side or the other (on a microscopic scale). This was preferred because it brought back the metal to its sharper state much quicker by restoring the existing edge.
A honing steel usually consists of a hardened steel rod with many tiny grooves scored lengthwise with a handle. It can also be made from a ceramic material specifically intended for sharpening hardened knives or a diamond steel, which has tiny specks of industrial diamond dust bonded to its surface. Both surfaces are equally effective for sharpening and honing the edges of knives, but they tend to wear away at the knife far more than do other kinds of steel.
To use a steel, the knife is drawn perpendicular across it’s surface, in a slow slashing motion, that both takes the knife across the steel while moving down the steel’s length, alternating sides of the knife with each pass. Holding the knife at the appropriate angle, about 15-25 degrees, to match the existing stone-cut angle, the first moves of the knife will feel slightly rough and resistant to the steel. Holding the knife at the same angle and applying the same pressure, that feel will diminish within five or ten strokes. That’s the steel telling you the job is done. A good steel will extend the life between stone sharpening by many months in most cases, although home cooking enthusiasts will find that a inexpensive steel will bring many knives back to life in moments.
THE BENEFITS OF MAINTAINING A SHARP BLADE
- Look for the highest and hardest grade of steel with the highest capability of sharpness (with increased hardness also comes increased brittleness. If the knife is dropped or used to chop bone, it is more likely to break or chip).
- High quality knives can have an edge sharpened to razor sharpness (capable of shaving human hairs), which can only be maintained briefly if the knife is in constant use. However, the level of working sharpness (where the knife can no longer shave hairs, but remains extremely sharp and will cut food items efficiently and effortlessly) will be maintained much longer than a steel blade of lower grade.
- Low-grade steel blades (e.g. less than 40° hardness) cannot ever sharpen to razor standard.
- Any form of knife sharpening involves the removal of material from the cutting edge. Once the knife is as sharp as the blade steel and the sharpening method will allow, further sharpening serves only to remove excess steel and reduce the working life of the knife.
- Any form of knife sharpening involves the use of an abrasive contact with the cutting edge to remove steel. After a time an undesirable shoulder will be produced (a distinct angle change between the cutting edge and the side of the knife blade). A good sharpening system will allow the operator to remove a shoulder and re-create a gradual profile.
- Any hard abrasive object i.e. grinding wheel, steel, diamond steel, oilstone or whetstone; will impart scratches to the cutting edge. The coarser the abrasive, the more pronounced and deeper the scratches.
- A knife sharpened on a coarse abrasive can still feel sharp. Indeed, for cutting some food items such as tomatoes, the rough edge will be extremely effective, but for cutting more fibrous items (e.g. meat for example, the rough edge will drag on the meat fibres, producing a rough cut and involving higher operator effort).
- Any sharpening method that does not guide the knife (e.g. sharpening steel or plain whetstone), relies on the operator to set and maintain the sharpening angle (bevel angle on the knife edge). In practice, this is virtually impossible and although a sharp cutting edge can be created, the original profile of the cutting edge will be gradually lost, as will the durability of the edge. Both the
- The bevel angle of the cutting edge varies according to different quality paring knife manufacturers. The minimum we know is 13°, the maximum 29°. The greater the angle, the greater the effort required to cut. Too narrow an angle would result in a fragile cutting edge. 15° is the best compromise.
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