One of the most frustrating things is cutting with a dull knife. I wouldn't write with a very dull pencil so why do I cook with a dull knife. I think most people are too intimidated by knife sharpening but it's really easy. Here's a quick way to sharpen knives using the unglazed, rough bottom of a common coffee mug:
The reason this works is because ceramic is harder than steel. Diamond is 100 on the hardness scale and cheap steel is about 50-60. Good, expensive steel is about 60-70. Ceramic (like the kind on your coffee cup) is about 85. This means that ceramic will actually scrape steel off your knife. It's like sharpening a pencil by shaving off a new edge. The gray material that forms on the cup is actually fine particles of steel being shaved off.
It actually works. I've done the knives at NL and they really are sharper. Good knives will maintain sharpness for a long time while cheaper knifes will require it more often. It's not as precise as using a whetstone with different grits. For an expensive/quality knife, I would take it to a skilled professional to make sure it's done right. For an average dull knife about 10 swipes each side will do nicely every once in a while. Just keep it parallel to the table and keep the blunt end lifted at about 20-30 degree angle and swipe it across the bottom of the cup. If gray marks appear, you're doing it right. It can't replace professional sharpening -- true sharpening has more steps and creates a smooth, sharp, and polished edge.
In what circumstance would I do this? On the fly cooking at someone's house and I don't have access to proper tools and want a sharp knife. When visiting family and they have DULL knives and I want to do something nice for them. I do this to my steak knives instead of taking out the full sharpening tool set. It actually works wonders on scissors. Spread the blades open and take each blade and swipe against the angle (sharpen only the existing sharp edge). My kitchen shears and the scissors at my work desk are very sharp now.
The next post will discuss honing a knife using a steel.