Tools which are going to be used in soft wood require rather a longer bevel and more acute edge than when they are wanted for hard wood. Both angles are shown in Fig. 8. Lay the flat of the tool on the stone at an angle of about 15°, with the handle in the hollow of the right hand, and two fingers of the left pressed upon the blade as near to the stone as possible. Then begin rubbing the tool from end to end of the stone, taking care not to rock the right hand up and down, but to keep it as level as possible throughout the stroke, bearing heavily on the blade with the left hand, to keep it well in contact with the stone. Rocking produces a rounded edge which is fatal to keenness. C (Fig. 9) gives approximately, to an enlarged scale, the sections of a good edge, and D that of an imperfect one.
[Illustration: C. GOOD CUTTING EDGE D. BADLY FORMED EDGE. FIG. 9.]
Practise alone will familiarize the muscles of the wrist with the proper motion, but it is important to acquire this in order to form the correct habit early. It should be practised very slowly at first, until the hands get accustomed to the movements. When one side of the tool has been rubbed bright as far as the cutting edge, turn it over and treat the other in the same way. Carvers' tools, unlike joiners', are rubbed on both sides, in the proportion of about two-thirds outside to one-third inside. When a keen edge has been formed, which can easily be tested by gently applying the finger, it should be stropped on a piece of stout leather. It will be found, if the finger is passed down the tool and over its edge, that the stoning has turned up a burr. This must be removed by stropping on both sides alternately. A paste composed of emery and crocus powders mixed with grease is used to smear the leather before stropping; this can either be procured at the tool shop, or made by the carver. When the tool has been sufficiently stropped, and all burr removed, it is ready for use, but it is as well to try it on a piece of wood first, and test it for burr, and if necessary strop it again.
Before we leave this tool, however, we shall anticipate a little, and look at it after it has been used for some time and become blunt. Its cutting edge and the bevel above it are now polished to a high degree, owing to friction with the wood. We lay it on the stone, taking care to preserve the original angle (15°). We find on looking at the tool after a little rubbing that this time it presents a bright rim along the edge in contrast with the gray steel which has been in contact with the stone. This bright rim is part of the polished surface the whole bevel had before we began this second sharpening, which proves that the actual edge has not yet touched the stone. We are tempted to lift the right hand ever so little, and so get rid of this bright rim (sometimes called the "candle"); we shall thus get an edge quicker than if we have to rub away all the steel behind it. We do this, and soon get our edge; the bright rim has disappeared, but we have done an unwise thing, and have not saved much time, because we have begun to make a rounded edge, which, if carried a little farther, will make the tool useless until it is reground. There is no help for it: time must be spent and trouble taken in sharpening tools; with method and care there need be very little grinding, unless tools are actually broken.