Will using a knife sharpener reduce the lifetime of the knife

Technique

• Always use a cutting surface made for a knife, particularly a wooden chopping board/block. Avoid contact with hard surfaces such as metal, glass, or stone; these will quickly cause dulling or even chipping of most knives. Also avoid cutting frozen items, for the same reason.

• Use the dull end ("top") of the knife for scraping food off surfaces, or use a scraper or spatula instead. Knives are meant to cut straight, along the edge; scraping one sideways across any surface will misalign the edge very quickly.

• Do not use more force than necessary. A sharp knife should cut with very little effort. The more pressure you apply, the faster it will dull.

• Use a cleaver for bones or other very hard foods. General-purpose chef's knives or smaller knives aren't appropriate for this task, and may chip or even snap.

General Care

• Wash or rinse knives promptly after use. The moisture in many foods can be acidic and/or corrosive to the metal (fruits, onions, etc.).

• Dry knives immediately with a soft cloth or towel. Stainless steel is resistant to rust and corrosion but not immune. This goes for all metal but especially knives, because even an imperceptible amount of rust along the edge will drastically hinder its ability to cut. Air-drying may also leave you with stains or "spots" due to salts and other trace minerals in the water.

• Store knives in a dry, open area, away from other objects, to avoid moisture build-up, impacts, and secondary rust.

• Do not put a knife in the dishwasher. A knife in a dishwasher is subject to impacts, corrosion, and warping of the wooden handle/joint. Quality knives should be hand-washed.

Honing

Honing a knife is a good way to restore a slightly dull knife. You will need an honing steel (sometimes misleadingly referred to as a sharpening steel), which can be bought inexpensively. Note that there are differences between steels; the best value tends to be in the $30 (USD) range.

Honing is not the same as sharpening. Honing helps to align the existing edge, which becomes skewed or "curled" after regular use. It will not help to create a new edge if the knife is damaged, e.g. if it is corroded or chipped due to not following the "General Care" advice above.

To hone a knife:

1. Keep the honing steel vertical.
2. Hold the knife at a slight angle to the steel.
3. Stroke downward and towards yourself.
4. Alternate strokes, and do an equal number of times on both sides.

Here is a video illustrating the technique.

Sharpening

Knife sharpening involves a whetstone (AKA sharpening stone) and is an art unto itself. Some knife manufacturers do explain the process, however, the technique takes a long time to master and most home cooks will prefer to leave this to a professional.

If you find that regular honing is no longer effective at maintaining a knife's edge - and if it's been well-maintained, this should take several weeks or months - then it's time to get the knife sharpened.

• An alternative to professional sharpening (or learning to use a whetstone) is to use a good-quality motorized electric sharpener, such as the Chef's Choice. This will obviously not yield the same result as a professional sharpening, but it is very convenient and fast.

  Some people believe that all electric sharpeners will damage your knives. This may still be true of the cheaper, single-stage sharpeners, because they do a lot of grinding and generate a lot of heat. However, the more modern, higher-end sharpeners operate very quickly, have precise angle control, and use multiple stages mimicking the manual process (grinding, steeling, stropping).

  The "grinding" stage on a multi-stage sharpener should only be used if the knife is already badly damaged, and will actually create a new edge. If your knife is in reasonable shape, then it's fine to use a good sharpener on a semi-regular basis as long as you don't grind too much. (Honing should still be your primary form of maintenance).

• Yet another option, if you're on a tight budget, is to use sandpaper. Follow the link for additional information on technique, grit, and tutorials.

Oh absolutely, you certainly don't want to sharpen a kitchen knife on a 200 grit stone! You'll want one medium stone in case you ever need to remove a nick or something (but then you should probably take your knife to a pro at that point), and then probably like 2000-4000-6000 grits for routine polishing. (Note Japanese grit numbers are different than American oil stones).