All edged tools require periodic sharpening. If you work with a dull blade, you'll have to work much harder for less dramatic results and you'll run the risk of leaving rough cuts and even injuring yourself. Flat blades can be sharpened using standard brick-shaped sharpening stones, but your hand tools with curved blades need to be sharpened on an India gouge sharpening stone. Though these stones were originally designed with sharpening gouge tools in mind, they work wonders on almost all curved blades.
Hold the India gouge sharpening stone in one hand and the handle of a curved blade tool in the other.
Sharpen the blade side of the tool by pressing it against one end of the stone and pushing it towards the other end. There are a few fine points to doing this; first, make sure that you begin each stroke on the end of the stone closest to your body and that you push it away from you, dragging it across the entire length of the stone. Second, you must turn the tool in the direction of the curvature of the blade as you push so that the entire curved blade surface gets sharpened with each pass. When it comes to tools like gouges, the blades of which form almost complete semicircles, you cannot easily hone the entire length of the blade in one stroke. These tools should therefore be turned in one direction with the first stroke, then in the other direction with the second stroke, and so on.
Continue sharpening the blade with long, fast strokes for at least 60 seconds. Then pause and feel the edge of the blade. If it still is not sharp enough, continue sharpening in 30 second increments, checking the sharpness of the blade after each increment, until the blade feels sharp to the touch.
Clean up the blade point using a slipstone. The slipstone should be rubbed against the opposite side of the tool as the blade edge; in other words, it should be used on the side of the blade that you did not rub against the India stone. In the case of sharpening a gouge tool, it would be slipped through the concave, bowl-shaped part of the tool. Run the full length of the slipstone along the blade point, turning the slipstone as necessary to ensure even strokes that touch all parts of the point. About 30 second of this treatment is enough to clean up any burrs left by the sharpening process.
Strop the blade by rubbing it against a leather stropping strap. Stropping the blade edge is easy; just run the blade edge along the length of the leather strop 30 to 40 times, turning the blade with each stroke to ensure that you cover the entire blade surface. Stropping the opposite side, the side you cleaned with the slipstone, is more difficult, particularly with gouges. You must hold the leather strop and run the corner or edge of it along the blade point. It can be hard to get the corner of the strop into the concave side of a smaller gouge, so be careful.