Pretty much anybody who has spent any time in a kitchen – home or professional – will tell you that the most dangerous thing to have in a kitchen is a dull knife.
Now this might seem counter-intuitive. After all, sharp objects are certainly more often associated with danger than are dull objects. But the reason is fairly simple; a very sharp knife will easily and cleanly slice through meat, vegetables, fruits, etc. with very little effort on the part of the knife wielder. Basically, the knife does all the work. Its a matter of kinetic energy – the energy the knife possesses due to its motion.
Very little energy is needed to move a sharp blade through, say, a potato. A dull blade requires more pressure – energy – to be exerted to achieve the same result. When you're talking about objects that are often wet, slippery, or odd-shaped – i.e. meats, vegetables, fruits, etc. – the more energy you exert, the more likely the knife is to slip, usually taking a piece of your finger along with it.
Another reason to keep kitchen knives sharp involves clean, even cutting. A sharp knife allows for precise, uniform cuts while a dull knife usually results in jagged edges and uneven cuts.
Recent personal experience: I was asked to prepare a meal in a home I was visiting. Since I almost always wind up cooking someplace, I almost always carry my knives with me when I travel. Not this time. I was at the mercy of the home kitchen.
In the first place, the knives were all strewn about in a drawer. In the second place, they were nearly all of the cheap discount store variety. In the third place, they were without exception exceedingly dull. I went through six knives of varying shapes and sizes. There was an eight-inch chef's knife, a santoku, a couple of utility knives, a boning knife, and a carving knife. The hostess even brought out a cleaver! After practically having to stand on several knives in order to get them to pass through a potato, I was on the verge of pulling out my Swiss Army knife when I finally hit upon one – a carving knife – that was almost sharp enough. Almost. The cuts I wound up with were not anything to which I would normally lay claim, but I managed to butcher six potatoes without butchering my hand.
Part of the reason for this is quality. If you are at all serious about cooking, you should invest in the best quality knives you can afford. This doesn't mean you have to take out a loan and buy a full set of Globals or Henckels or Wustofs. But you should avoid the discount store sets that include twenty-five pieces – including a full set of steak knives – for ten dollars. Victorinox makes a number of good knives for reasonable prices. If you've got a couple of bucks to spare, you can buy one or two of the higher-dollar knives from open stock at most culinary stores or places like Bed, Bath and Beyond or Williams-Sonoma.
Among the best tools I own are four Ekco Eterna knives that I inherited from my mom's kitchen. They are at least fifty or sixty years old, but they still outperform many of my other blades. Things were made so much better in those days. Quality really does count.
However, proper care is also essential. It doesn't matter how good your knife starts out – how sharp it is, how expensive it is, how pretty and shiny it is – when you throw it in a drawer with the spoons and spatulas and what have you, you are going to ruin it. Period. Constant rubbing and bumping against other objects will dull and pit and nick the blade, rendering the knife useless. That's why they make knife blocks.
Knife blocks come in all kinds of designs. Most are made of wood or bamboo and have slots of various sizes, although there are “slotless” polycarbonate knife blocks on the market. These are all great for keeping your knives organized and in relatively good condition. I say “relatively” because the slotted blocks can – and often do – dull your knives by the repeated sliding action. Even the polycarbonate brushes in the “slotless” jobs will scratch and dull your knives over time. Another drawback with knife blocks relates to sanitation. They are impossible to clean. Stuff can accumulate in the slots and you'll never get it out. Moisture can be a problem, too. Even so, a knife block is far superior to loose storage in a drawer.
Superior to a knife block is a magnetic knife strip. Now, I have heard one or two people talk about damaging their knives on a magnetic strip. It can be done – if you are a careless, blithering idiot. The only way to damage a knife on a magnetic strip is if you slam the knife onto the strip edge first. You should place the knife on the strip, being careful to let the spine make first contact with the magnet and then ease the rest of the blade onto the strip. And don't drag the knife along the strip when you remove it; lift it straight off. You'll never damage a blade and your knives will stay clean and dry.
Another key element in proper knife care is cleaning. Never – let me italicize that – never put a knife in the dishwasher. (A) – There's a lot of banging around that goes on in there. (B) – The extreme heat inside a dishwasher can damage your knife, especially if it has a wooden handle. Wash knives separately by hand and either dry them immediately with a clean, soft towel or allow them to air dry. If your wooden knife handles seem to be drying out, regular treatment with mineral oil will keep them in good shape.
I was ten or eleven when I learned how not to wash a knife. Actually, my grandmother was washing; I was drying. I took the knife out of the rinse sink and, with the towel draped over my open palm, ran the spine of the knife and one side of the blade over the towel. Then I turned the knife over and ran the other side of the blade and the edge over the towel. Fortunately, I didn't require stitches. And I never did anything that stupid again.
Which leads to another safety point – besides the obvious one I just made; don't throw a knife in the sink with all the other dishes. In the first place, there's that jumbling everything together and causing damage thing again. And, with all those dishes and all that soap in the water, you're really likely to reach in there blindly and grab a handful of the wrong side of the knife. Sort of been there, done that. Not fun.
Wash knives individually. And wash them quickly. Acidic foods – tomatoes, citrus, etc. – can be corrosive if left too long on the surface of a knife blade. I wash my knives as soon as I'm finished using them. They never go in the sink with other dishes and they never see the inside of a dishwasher. If something does stain your knife, use a fine abrasive pad – like a Scotch Bright pad – to gently remove the stain. Do it right away before the stain penetrates the surface of the blade.
Preserve the edge on your knife by being careful about your cutting surface. Marble and glass cutting boards are so pretty and attractive in your kitchen. And nothing will dull your knives faster. Wood or bamboo are still best, although plastic boards are okay, too. I like wood, my wife likes plastic so we have a kitchen full of his and hers boards. But we both have very sharp knives.
And we keep them that way by regular honing and sharpening. Honing involves the use of a metal or ceramic rod usually called a “steel.” Gordon Ramsay doesn't do all that fancy stuff with the steel just to impress his audience. It has a real purpose. (Well, maybe Gordon is a little over the top about it; a few light strokes on the steel are all that's needed.) Honing with a steel, however, is not the same as sharpening. That's why the term “sharpening steel” is a misnomer. A honing steel removes little micro-serrations that develop on the knife's edge and actually straightens the blade. A steel should be used before and/or after any cutting task. There are lots of places online where you can learn about how to use a steel.
Sharpening, on the other hand, is done less frequently and usually involves a whetstone. Sharpening a knife on a stone is an art and a science. It is a practice which most casual cooks – and many pros – will never master. That's why there are a wide variety of knife sharpening devices on the market. Some are really good and some are really a waste of money. Do your research and buy the one that best fits your needs and your budget. Or do as many of the pros do and have your knives professionally sharpened from time to time. It won't be cost-effective if you have a five-dollar Walmart knife, but if you dropped a hundred or more on a Wusthof, you'll want to make the investment.
Your knife is your most important kitchen tool. Keep it sharp, keep it clean, and keep it properly stored and you'll keep it for a lifetime.