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Japanese Knife Polishing

Traditional Sword Progression

Kongo -> Omura -> Binsui – > Kaisei -> Chu -> Koma -> Awasedo -> Uchigumori

General Process

You need to first determine if the blade is a convex, hollow, or flat grind. That will determine how you work on the stone. If it is convex, you need to work it in a certain way (like a rocking motion usually on convex stone). If it is hollow, you either need to work on convex stones or flatten out the hollow grind. If you are flat grind, you will need to work out low spots. All of this process though will start at the lowest end of the spectrum you have on hand, many start in the 80-140 range. Synthetics or diamond products are best until around the 1k-2k spot (without contest, naturals below that level often are just leaving deeper scratches than you want and will take forever to work out in the 3k+ range – it is possible to use full naturals but increase your time investment by a factor of x3) and whether you transition to naturals after that is up to you. Naturals will still be slower at any stage you transition too, but I personally like naturals myself after that 2k area. You can use the marker test as you move between steps, where you color in the whole “to-be polished” surface with a sharpie to be able to identify once you have fully worked that entire surface of the knife on the stone. If you fail to do properly touch up the entire section to be polished at one step – like missing a low spot – you will not be able to fix it at the next step. The lower grit steps are the most important as they set you up for success in your subsequent steps.

Obviously from there, you work up through your stones to your finest. Most people really transition fully to natural stones around the 8k range I suspect. Softer stones will be easier to work with, and you have to be careful as an inclusion or poor technique can set you back once you hit this stage. Often people find they messed up somewhere, and if you need to just return the knife to serviceability and look okay, I suggest you pick up or make some finger stones. In the start of things (or heck even when more experienced) they can be very useful for evening out polishes or hard to reach areas if you don’t have time or do not want to restart.

There are many who are far better at polishing than me and I hope they speak up. Those are the broad strokes from my experience. On that note though – nothing replaces experience. You are going to mess up, you are going to learn lessons the hard way, and you are going to have to spend many hours on the stones before you really start to grasp it. Try to keep it fun and don’t beat yourself up.