Knife Sharpening Tips

A knife is useless if it is not sharp and sharpening a knife is sometimes perceived to be the most difficult knife care task there is. You can tell if your knife is sharp if it can cut through a tomato with easy. When the edge of a knife gets dull after repeated use, the cutting edge of the knife will get bent out of alignment. The harder the metal the knife is made of, the harder it will be to sharpen the knife but the longer it will hold its sharpness. An example of this is the stainless steel knives that most modern knives are made up of.

When sharpening a knife you must have a high quality sharpener that features a rough surface with a finishing surface of hard stone or ceramic abrasive. The harder the metal the knife is made of, the harder the sharpening tool has to be made of to abrade the knives edge. You can measure the hardness of the metal using the "Rockwell Scale."

Step 1: Using a coarse grinding stone. For use on knives with heavy nicks and extremely dull blades:

Rub some mineral oil on the grinding stone to keep the stone grindings loose so they do not seal and glaze the surface of the stone. Start at the tip of the knife and apply strong pressure down and forward so the whole blade is in contact with the sharpener so the cutting edge abrades against it. If you hold the knife against the stone to cut evenly across the edge grind, you will produce an edge with a similar angle. A good rule is to hold the blade so the back of it is about one blade width up from flat on the stone. Remember to apply steady and strong pressure and keep the angle constant. Too much pressure will remove the grit from a diamond sharpener. The blade edge should be facing in the same direction as your stroke so that you move the metal away form the edge of the knife. Remember to alternate the blade sides. Do the same number of strokes on each side of the blade but do not alternate sides with each stroke, or you will not get a burr. As the knife gets sharper and thinner at the end, go to a finer stone.  When you are through clean the knife. If you have nicks work those separately. If there is a nick, you can work around the nick evenly from side-to-side. Once the nick appears to be gone, go back to working the entire length of the edge.

Step 2: Using a fine grit sharpener such as a ceramic sharpener:

This step if for the typical dull blade or after using a grinding tool to remove rough scratches from the grinding tool. They can be used dry or wet, however, if you are going to wet the sharpener, use water-based or petroleum-based honing oil. You can sharpen the edge of the knife following the same steps as in step 1. If you can achieve a good, sharp edge and finish to the knife, you do not have to go to step 3. To do this, hone with a light, single strokes, side-to-side, until you feel no burr on either side. To smooth the sharpening scratches go to step 3.

This step is for slightly dull blades, or to help remove any remaining burr and put a burnish on the blade edge. With natural sharpening stones they can be used wet or dry, however, wet is the recommended choice. Water based or petroleum-based honing oil is best here as well. This is to keep the pores of the stone clean, and dissipate frictional heat and this will ensure smooth sharpening action. As a reminder, once you use an oil based sharpening fluid on natural or aluminum oxide stones, it is difficult to change back to using water. When using the oil, make sure you are generous with the oil. Use enough to keep visible to keep a pool visible on the stone while you are sharpening. You will want to use the same stroking method as described in step 1.  Repeat until all scratches are gone. Although you will still feel burr, it should be smaller and finer.