Keeping your knives sharp is the best way to ensure their longevity. There are many techniques you can use to sharpen and care for knives.
Traditionally, knives were forged from carbon steel, a mixture of iron and carbon. Of the materials used to make knives today, carbon steel is the least expensive and easiest to keep sharp, but it rusts, stains, and darkens when it comes into contact with humidity and acidic foods. Stainless steel remains unblemished under these conditions, but its hardness makes an edge difficult to sharpen and maintain.
The compromise is a high-carbon stainless mix of surgical steel, molybdenum, vanadium, nickel, and chromium that resists corrosion and also provides increased flexibility. The Rockwell Scale, a measure of hardness for steel, serves as a consumer guide: A knife rated 55 to 58 degrees both sharpens readily and sustains an edge; a higher rating means that an edge lasts longer but is too difficult to achieve; below 55 degrees, a blade is too soft to hold an edge.
After it is forged, the entire blade is ground or tapered so its thickness gradually decreases from the handle to the tip. To see this, look at the top of a knife with the cutting edge down. A slim taper strengthens a knife, making an edge easier to acquire and maintain, and creates a tip that penetrates easily. Some stamped knives are also taper-ground, but most lesser models will have either a fat taper or none at all. The best edges are completely beveled and taper to a fine point at the end of the blade.
It is best to wash and dry knives by hand. Rub off any stains with a clean wine cork dipped in a household cleanser; a mixture of coarse salt and lemon juice or vinegar also works well.
Knives must be properly stored to maintain their edges. A wooden countertop block or drawer tray with slots isolates each blade. Use a knife guard as an alternative. If you are storing knives in an open drawer, make sure it is lined with a nonslip material.
A few strokes on a sharpening steel are necessary before each use. Contrary to popular belief, a sharpening steel does not sharpen a knife as much as it resets, or realigns, the edge. Although steeling is faster on a coarse steel, a fine steel produces a smoother finish. Any steel can be used horizontally or vertically. If steeling vertically, anchor the steel in a damp towel.
Place the heel edge of the knife behind the steel at a 20-degree angle (to find 20 degrees, hold the knife edge perpendicular to the steel at a 90-degree angle, then tilt the knife halfway up for a 45-degree angle, then halfway up again); now slide the entire blade down the length of the steel while pulling it sideways from hilt to tip. Place the knife in front of the steel; repeat.
To steel a knife horizontally, hold the knife in the cutting hand with its blade perpendicular to the steel, which is held in the other hand. Find a 20-degree angle, and move the knife across the steel from heel to tip. Turn the knife over; repeat. Ten strokes on each side are usually sufficient. A steel is magnetized to attract particles, so store the steel separately from knives.
A knife should also be sharpened several times a year on a stone. A rectangular Carborundum block with medium-coarse and medium-fine grit is most common. Before using, cushion the stone in a damp towel, lubricate it with oil, and orient it with a short side toward you.
Start with the coarse side up; lay the heel of the blade on the bottom right-hand edge of the stone. Sharpen the entire edge by holding the knife at 20 degrees with one hand while guiding the blade with the other. Turn the knife over, and repeat, starting with the heel of the blade on the lower left-hand edge of the stone. After 10 to 20 swipes on each side, use the fine-grain side to keen the edge.