Written by Maksim
How to get a beautiful kasumi finish using hard Japanese natural stones
Kasumi on hard Jnats is quite difficult to make — but possible, and the result is better than what you get from soft stones. The finish on harder Jnats is finer and more mirror-like, but still with that beautiful distinction between the hard steel (hagane) and the soft iron cladding (jigane) that makes Japanese knives look so special.
What is Kasumi?
Kasumi (霞) means mist or haze in Japanese. It refers to the hazy, cloudy polish on the soft iron cladding (jigane) of a clad Japanese knife. The hard steel edge (hagane) polishes to a bright mirror while the jigane stays hazy — the contrast between the two is what gives a traditionally finished Japanese knife its beautiful look.
Why Hard Stones Are Difficult for Kasumi
Some super hard stones will scratch your soft iron (jigane) and ruin your finish — but not all of them, and it also depends heavily on your technique. The problem is not the stone itself. The problem is that hard stones need very specific conditions to produce kasumi rather than scratches on jigane.
Soft iron is softer than the particles in a very hard Jnat. If you use a hard stone dry, with too much pressure, or without slurry — those particles cut into the jigane aggressively and leave deep scratches. But with the right slurry and light pressure, the same stone gives a finer and more beautiful kasumi than any soft stone could.
This is why beginners should learn kasumi on softer Jnats (Lv 2–3) first. Once you understand how slurry and pressure work on softer stones, then you can move to harder ones and get the best possible kasumi finish.
How to Get Kasumi on a Hard Stone
These are my tips from experience. Follow all of them — skipping even one will give you problems !!!
The slurry should be a paste, not watery soup. Too much water washes away the slurry and the stone cuts too aggressively. Too little and you get friction and overheating. One or two drops at a time from your finger. Let the slurry build up before adding more water.
Light pressure only when working the jigane. The slurry does the polishing — you only guide the knife. Heavy pressure bypasses the slurry and lets the stone particles cut directly into the soft iron. This is how you get scratches instead of kasumi.
A dished stone or uneven bevel means some parts of the jigane get more pressure than others. This creates uneven kasumi at best, scratches at worst. Flatten your stone properly before attempting kasumi work. See the How To Use Guide for flattening technique.
Short strokes give you more control over pressure and angle. Long strokes make it hard to maintain a consistent angle on the jigane and you risk lifting the edge and scratching. Short back-and-forth strokes, keeping the blade very flat on the stone.
A Botan or Mejiro nagura raised on the stone before you start creates a slurry buffer between the stone and the jigane. This dramatically reduces the risk of scratching. As you get more experience you can work with less nagura and more direct stone-on-jigane contact — but start with nagura !!!
The biggest mistake I see — going to a hard stone before the previous stone's work is complete. A hard Jnat is so fine that on the first passes it immediately reveals scratches from softer stones. People see scratches and think the hard stone is scratching the jigane — but actually those scratches were already there from a medium stone. Finish properly on each stone before moving up !!!
Which Hard Stones Work for Kasumi
Not all hard stones are equal for kasumi work. Here is what to look for:
- Smooth surface. A hard stone with a naturally smooth feel (not scratchy) is much better for kasumi than a hard stone that feels coarse on the surface. The surface texture of the stone affects the jigane even when using slurry.
- No toxic lines or hard inclusions. Hard dark inclusions (toxic lines) will scratch the jigane no matter how careful you are. Avoid these on stones you plan to use for kasumi. Check the product listing carefully — I always note when a stone is free of inclusions.
- Lv 3.5–4 for beginners on hard stones. You do not need to go to Lv 5 to get great kasumi. A Lv 3.5–4 stone gives excellent results and is much more forgiving. Start here and move to harder stones as your skills improve.
- Hard Nakayama Asagi and Ozuku are excellent. These are the classic hard kasumi stones. When used correctly with nagura and light pressure, the kasumi they produce on soft iron is extraordinary — finer and with more depth than anything you can get from a soft stone.
Video — Ozuku Asagi Lv 5+ Kasumi Result
Here is a short video showing a super hard Ozuku Asagi Lv 5+ and the kasumi finish it produces on a Japanese kitchen knife. You can see how the technique and slurry management produce a beautiful result even on a very hard stone.
Ozuku Asagi Lv 5+ — kasumi finish on a Japanese kitchen knife
That is it :) It takes practice but once you get it right there is no going back to soft stones for kasumi work. If you have questions about your specific stone and knife combination, message me on WhatsApp.