Slideshow: Knife Skills: How to Sharpen a Knife

Step 1: Work in Batches
Step 1: Work in Batches
Although it's worth the effort, knife sharpening can take a bit of effort and time. If you're going to be setting up and breaking down a station to sharpen a knife, think ahead and sharpen every knife in your kit that may need sharpening to get the whole process done in one session instead of several.
Step 2: Soak your Stones
Step 2: Soak your Stones
When working with water stones, it's essential to submerge them in water for at least 45 minutes before using. If the porous stones are not fully saturated, they will dry out during sharpening, causing the knife blade to catch, and giving your edge nicks and dings. Soak both your stones, and your stone fixer.
Step 2: Set up Your Station
Step 2: Set up Your Station
Place your stone on a towel set over a cutting board. Keep a container of water nearby to keep your stone constantly moistened during the sharpening process. The stone should be oriented with the short end parallel to the edge of the counter.
Step 5: Maintain Angle
Step 5: Maintain Angle
Be careful to maintain the 15 to 20 degree angle as you pull the knife across the stone. Pressure should be firm, but gentle. The blade should glide smoothly across the stone as you pull.
Step 6: Finish Stroke and Repeat
Step 6: Finish Stroke and Repeat
Each stroke should finish with the tip of the knife touching the bottom of the stone. Lift the knife, reset the heel at the top of the stone, and repeat.
Step 7: Look for Silty Water
Step 7: Look for Silty Water
As you repeat the process, a thin film of silty looking water should collect on top of the stone and on the blade. This abrasive liquid will gradually take material off the edge of your knife, sharpening it.
Step 9: Start Sharpening Second Side
Step 9: Start Sharpening Second Side
To sharpen second side, place the heel of the blade near the base of the stone, again maintaining a 15 to 20 degree angle. Gently push the blade away from you while simultaneously dragging across the stone towards the tip.
Step 10: Finish Second Side
Step 10: Finish Second Side
Your stroke should end with the tip of the blade against the top edge of the stone, still maintaining a 15 to 20 degree angle. Remember to moisten your stone between strokes if it begins to dry out. Repeat for as many strokes as it took you to form the burr on the first side.
Step 11: Fix Stone
Step 11: Fix Stone
After repeated use, your stone will begin to develop grooves in it, which can hinder its sharpening power. To fix it, use a low-grit stone fixer. Place the fixer flat against the stone, and push it back and forth to grind down the stone and create a new, flat surface.
Step 13: Hone and Test Your Blade
Step 13: Hone and Test Your Blade

After sharpening, hone your blade on a honing steel in order to get the edge in alignment, then test it for sharpness. Some people recommend trying to slice a piece of paper in half by holding it up and slicing through it. I find that even a relatively dull knife will pass that test, yet fail at other kitchen tasks.

The best test is to simply use the knife to prep a vegetable. Do you notice any resistance? Does it fly through that onion? Can you slice a ripe tomato thin enough to read through it? Yes? Then you're done!