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Surface Polish

This section discusses the surface polish of a katana and what grit abrasives are used.  The surface polish of a katana is as important to cutting as the geometry.  It is especially important for the durability of the edge and surface friction of the blade.  An edge from a coarse grit stone may feel very sharp and cut well for the first few times, but it will quickly become dull. A rough finish will also bind up in the target.  Polishing and sharpening a katana are the same process.  For swords that will see real use, a full cosmetic polish is not needed.  Who wants to pay $2000 every year to keep your sword sharp.  A sharpening polish leaves some scratches on the surface and skips the purely cosmetic steps.


The first thing everyone asks is what grit stones are used to polish or sharpen a sword.  What could be easier than selecting an abrasive?  Is that US, European, English, or Japanese grit?  Are you specifying the mesh used to separate the particles or the particle size.  Everyone uses a different standard and they don't compare well.  Here is the results of my research into grit.

Equivalent Grit Table

0.5 12000 25000 Chromium Oxide Polishing Compound, Moor White Ceramic
1 5000 10000 Honyama Awasi (Brown Stone), Linde C Compound (Aluminum Oxide Powder)
2 3000 6000 Karasu (Blue Stone), Awasi Toshi
3 2000 4000 Uchigumori, Extra Fine White Ceramic, Green Chrome Rouge, Spyderco Extra Fine Ceramic
6 1200 2500 Ao-To (Blue Stone), Spyderco Fine Ceramic
10 1000 2000 Hard Black Arkansas, Extra-Fine Diamond Hone, Lansky Ultra-Fine Hone
15 800 1500 Koma-Nagura, Hard White Arkansas, Extra Fine Diamond, Medium Ceramic, Moor Black Ceramic
20 600 1000 Soft Arkansas, Lansky Fine Hone, Ultra Fine Scotch-Brite Pad, Spyderco Medium Ceramic
25 480 800 Chu-Nagura,  Washita Stone, Fine Diamond
35 320 500 Kaisei (Natural Sandstone), Fine India, Medium Diamond, Super/Extra Fine Scotch-Brite Belt/Pad
45 280 400 Medium India, Fine Crystolon  (Silicon Carbide), Coarse Diamond, Lansky Medium Hone
60 220 300 Binsui Coarse Stone, Extra Coarse Diamond Hone, Very Fine Scotch-Brite Belt/Pad
80 180 260 Fine Scotch-Brite Belt/Pad
90 150 220 Medium Crystolon (Silicon Carbide), Coarse India, Medium Scotch-Brite Belt/Pad
110 120 180 Arato (Natural Sandstone Or Carborundum), Lansky Course Hone
150 100 150 Coarse Crystolon (Silicon Carbide)
180 80 90 Lansky Extra Coarse Hone, Coarse Scotch-Brite Belt/Pad

If a sword just needs to be touched up, we use six progressively finer grits from 800 to 12000 (Japanese).  The polished surface is degraded if the edge is touched up with anything coarser.

Water Stones

Japanese water stones are either natural and artificial.  Natural stones can be quite expensive, but artificial stones can be used for sharpening polish.  About half the stone used in a full cosmetic polish can also be artificial, but some steps require specific natural stones.  Artificial stones use a graded abrasive suspended in either a clay or ceramic media.  The stones use water as a lubricant.  A series of stones ranging from about 800 to 12000 grit are used to sharpen blades in good shape.  If a blade is badly shaped or has chips to remove, stones down to 80 grit can be used.  Water stones should be soaked for 15 minutes before use.  Mixing baking soda in the water will help reduce corrosion of the blade during sharpening.