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After the blades were hardened, we began to polish with stones. For this I recommended using red brick EDM polishing stones in 120,220,320,600 grits. I buy my stones from Manhattan Supply Company. These stones are designed for tool and die makers to clean up molds and dies. They are a synthetic stone and quite soft, but they cut well and are very useful for cleaning up and polishing blades. I use then on all my blades and find they are especially useful for cleaning up the transition radius between the flats and ricasso on western style knife grinds. With price of sheet abrasive going through the roof, stones are a fine alternative. The stones wear more evenly and cut best when used with a light touch. I add a synthetic grinding fluid to the water to keep them from loading. I first heard about these stones from Steve Hoel, a superb folder maker. Steve stones and hand finishes all his blades and achieves amazing tolerances in his folders. Our objective with the stones is to polish out the file scratches, moving from the coarser grits to the final polish.
When polishing with either stones or paper, it is best to work at a 45 degree angle to the blade and reverse the direction with each change of grit. By polishing at different angles you can see the previous scratches and insure that all of them are removed before moving on. I also like to reverse the direction of sanding from the bevel and the back so I can clearly see my lines. It is sometimes hard to see all the scratches and I recommend working in a good light. I have a combination of natural light coming from a window by my bench, indirect light provided by florescent lights and a direct light source that can be move to different angles so that you can see the blade in all aspects. It is amazing how those scratches can hide in the light and one thing you can be sure of is that they will never go away if you miss them.
After I have set down a good 320 grit polish with the stones, I will switch to Japanese style water stones. I am not a sword polisher and can not justify the expensive natural stones a professional polisher uses, but am quite satisfied with the synthetic stones now commonly found in woodworkers supply catalogs. They also come in a variety of grits, but I use only the 400 and 800 grit. These stones need to be soaked in water before they are ready to use. I prefer to use distilled water and recommend adding a bit of baking soda to the water to help prevent rusting. I also have found it helpful to buy some plastic trays and keep each stone in its own tray. This helps prevent contamination by grits from the coarser stones.
The water stones are usually quite large 3x6x1 inches and I have found that they are more easily handled and that I can get more life from them if I cut them to smaller sizes using a masonry blade in my saw. The water stones cut very differently than the EDM stones. You will notice the hardened and unhardened portions of the blade pop out when you begin using these stones. Still alternating the direction of the strokes for each grit, I get a good 800 grit polish over the entire surface of the blade. These stones wear quickly and care must be taken to keep them flat so that they won't wash out the bevel lines. Also, the motion with these stones is to the edge, rounding in to sharpen as you polish. Be very careful not to slip or you will christen the blade with blood.
After the final water stone is finished, I switch to 600 grit wet or dry paper, wet and sand length wise on the blade. I cut the sheets into inch or so wide strips and pinch them over a sanding block of hard flat material. I like Corian blocks because they are not bothered by the water and are flat and thick enough to get your fingers on. I make my sanding blocks 1 inch wide and around four inches long. The paper is used wet with considerable force and the paper is rotated frequently as it begins to lose its cutting action. During this process the edge will begin to polish brighter than the softer back and you should continue to polish until all the scratches have been removed and the back is beginning to shine. While this process may seem to take forever the first time you attempt it, it gets much faster with practice.
At this point a light etch will really help pop out the temperline. I use a very dilute wash of ferric chloride , Archer etchant from Radio Shack, cut 2 to 1 with distilled water. I soak a portion of paper towel and rub it briskly over the entire blade. I am not trying to etch the blade as much as bring out the temperline. You have to acquire a touch with the ferric so that you don't darken some areas more than others, but it doesn't take long to figure out and can really make the temperline jump. When you are satisfied with the etch, rinse the blade and neutralize the ferric with a spray of ammonia. You can tell the ammonia is working by the blue green colors it turns up. Rinse again and dry the blade thoroughly.
The next step is 1500 grit wet or dry paper. I get these papers from my local auto parts store, but they are readily available. Again using this paper wet, go length wise over the entire blade paying more attention the area above the temperline than below. This will bring the back of the blade into high polish. If you wipe out the temperline redo with the ferric and repolish.
The final step is to go over the back of the blade with a fine paste polish. Some folks use rubbing compound on a cloth, but I like to use Simichrome a chrome polish found in most motorcycle shops or through mail order knife supply catalogs. Continue with the paste until the back of the blade is dark and all the 1500 grit scratches are wiped out. You can go over the hardened portion, but only lightly to remove the oxides from the etch. A popular finish on the Japanese blades shows a frosted edge, bright hamon and darkly polished back. You can approach this look with careful use of the paste polishes. Another polish used to darken the back of the blade can be made by using red rough buffing compound and light oil.
Now is the time to look over your work. Carefully inspect the blade for areas that need work. It is helpful to look at the blade in full light and also indirect light, tipping the blade so that the hamon is clearly visible and so that you can inspect the surface from every angle. If you find an area that needs work go back to it until it is right.
This blade finish is quite attractive, easy to maintain and a lot less expensive than a traditional polish. While nothing can duplicate the incredible view into the metal that a well done traditional polish reveals, this method is attainable by anyone with simple tools and the willingness to work.
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