by Robert Benson (excerpt from Bushido MagazineVol.1,No.4)
Everyone that has a Japanese sword has uchiko. Generally of the commercial grade bought from a sword shop and we use it not giving much thought to how it is made. The commercial uchiko is not of the quality that can be gotten from a polisher as it is usually made the fastest way possible so as to keep the price down. I have had several people ask me why I don't make and sell uchiko. The main reason is that the cost would be too high due to the many man hours expended in the making. Most collectors have no idea of the work involved and don't even know what it is made from. For this reason I have written the following information along with pictures to show the process of making uchiko.
Uchiko is the powder made from the uchigomori stones,hazuya and jizuya ( final two stones used in polishing). Every polisher uses an omori stone to cut his hazuya and jizuya stones down to thin pieces so they can be rubbed on the sword and not scratch the metal. In Plate 1 is shown an oke or suibako (waterbox) with a large omori stone in the middle. On top of the stone are three pieces of hazuya and one piece of jizuya. The pieces will be ground down until they are about 1/32 of an inch thick as shown in plate 2.
The juice or ground off mixture of water and stone goes over the side of the omori stone and settles in the water box. After about three or four months of cutting down the stones there will be about an inch of sediment in the bottom. The time involved thinning the pieces over this three to four month period will be about eight hours.
When you have enough stone sediment to make three or four good size uchiko balls the flotation process can begin. The sediment is stirred up so there are no thick muddy pieces and then the mixture is poured into a metal pan or container that can be used to transfer the water and light pieces and catch the heavy omori stone particles. I use gold mining pans that are about four inches deep and twelve inches across the top. These are ideal for catching the heavier sediment.In Plate 4 the filtration process is in progress. The light uchigomori, hazuya and jizuya powder will be suspended in the water and poured with the water into another pan leaving all the heavier particles sinking to the bottom. After each transfer the pan is rinsed out so no heavy coarse pieces will contaminate the next pouring it is to 
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This is a sample of one of the articles in the 9 issues of Bushido Magazines. These magazines were originally published by us from 1978-81. They contain many informative articles for both the beginning and advanced collectorof Japanese Swords.
Reprinting of any article or portion of Bushido Magazine articles is prohibited without the permission of the publishers. contact benson@bushidojapaneseswords.com