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Change to a finer grit and repeat the above process. Once the back has been ground flat with the first grit, it gets much easier and goes much faster. It's a good idea to angle the blade slightly while working on the back and to change the angle with each successive grit. That way, you can readily see when you've honed off all the scratches left by the previous grit; another clue that it's time to change to a finer grit.
Check the blade to be sure that it is staying square. If it's not, push a little harder on the high corner while honing the bevel to bring it back square. Proceed through the grits until you run out of them. After a few, the honed surfaces will begin to act as mirrors; a sure sign of imminent sharpness. For most efforts, the 2000X paper is as fine as you need to go. But if you're doing the final planing on a surface that you don't want to degrade by sanding, you may want to go beyond the 2000X paper to a 6000X waterstone or a strop charged with chromium oxide compound (“green oxide” or “knifemaker's green”). The 6000X waterstone is a soft “stone” of cerium oxide that cuts fast but can be tricky to use because the blade wants to stick to the fine surface. Slow strokes, plenty of water and patience are required. The strop can be leather, cardboard, or wood; a flat, fine textured surface that will take the crayon-like super-fine abrasive is what you want. It's best to gently pull the blade across the strop or you risk cutting into it. Be careful to keep the back flat against the stone or strop and the bevel at the correct angle; you don't want to round off the edge. To test for sharpness, you can always shave the hairs on your arm (or wherever). A sharp edge will cut hairs with very little pressure. But if you're running low on hair (or just hate that patchy look) there are other ways. A sharp edge will catch on the flat of a fingernail or plastic pen barrel while a dull edge will skid a bit. It's really that simple; try it a few times to feel it but it takes only the lightest touch and if it skids, it's dull.
Also, you can see if a blade is sharp. Closely examine the edge with good light and if the edge reflects at all, it's dull. (Remember that zero-radius stuff? It's the blade's edge radius that reflects light and if there is no radius -- The Goal -- there will be no reflection.) If you've just done a chisel, block-plane blade or other breakerless blade, you're done! But if you're working on a bench-plane iron, you're not done until you've polished the breaker. Make sure the breaker, when tightened in position on the blade, makes complete contact along its edge with no daylight showing; no gaps at all where a shaving could catch. Now polish the breaker ramp-surface. How much work is needed depends greatly on its condition, of course, and how smooth is enough is a matter of experience and performance. Use the same abrasives starting no coarser than you must. Breakers usually aren't hardened so the work should progress quickly. Rock and slide the breaker along the different grits until all coarse scratches are gone and the ramp area looks and feels smooth. Now you're done. Resharpen often and lightly, no coarser than necessary, to insure good cutting performance and save time in the long run. Good luck, have fun, and... “Ommmm” Ron Hock
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