Japanese Knife Finishes

In your search for the best Japanese knife, you often come across terms like Damast, Tsuchime, and Sanmai. These are different finishes that the blade can have. Read more about all about the different types.

Mono-steel

These knives are made from one piece of steel, like the German knives from Wusthof and Zwilling. These knives usually have a hardness of up to 58 HRC.

Making a knife with a single piece of harder steel is possible, but the blacksmith needs to use a different technique called Honyaki.

Honyaki

Honyaki is a technique mastered by only a few masters in Japan. It is a time-consuming and expensive technique.

A blade made from a single piece of hard steel is very brittle and can break easily. A blacksmith can use a differential hardness technique to make the knife less brittle during the forging process.

With the differential hardness technique, they cover the upper part of the knife with clay. The clay keeps that steel cooler and makes the steel less hard and brittle.

Sanmai / Warikomi

A Sanmai / Warikomi knife is In the Sanmai technique, several layers of softer steel (Jigane) protect the core steel (Hagane). The protective layers can be made of carbon steel (carbon) or stainless steel. A hairline (cladding line) is visible on the blade where the protective layers end.

Without these layers, the knife would be too brittle and stiff. Because of the protective layers, there is less stress on the blade, and it will not break easily. The knife is also easier to straighten during forging if it deforms.

The difference between Sanmai and Warikomi

There are two ways to combine the protective layers to the core steel.

Sanmai

Sanmai is the most common technique To sandwich the different layers of protective steel on the core steel. The back of the blade is not covered, and you can see the different layers of steel. You won't notice this in use, and it doesn't affect the quality of the steel.

Warikomi

In Warikomi, they forge protective layers into a single piece of steel. After that, they split the steel down the middle and place the core steel (Hagane) between them. It covers the back, so you don't see any layers on the back like with the Sanmai technique.

Damask / Suminigashi

Damask is a more luxurious version of Sanmai processing with more layers. The extra layers do not provide additional protection but give the knife a unique style. Damask can be shaped in different ways and shows the skills of a blacksmith. They take inspiration from nature, art, and the suminagashi technique for the patterns.

Nice to know

Suminagashi is an art form in which paper is colored with ink floating in the water. A beautiful, fluid interplay of lines is the result. .

Blacksmiths in Japan continue to experiment with damask. Blacksmiths such as Nigara and Takeshi Saji forge steel with copper and nickel to make colorful damask. Other techniques involve putting the steel in an acid bath to make the damask darker.

Beware of counterfeit damask; the lines are made with a laser or by printing. This technique is done on cheap knives to make them look expensive.

PS.
Today's damask steel is not the same technique used centuries ago. You can read more about the origins of damask on this Wikipediapage.

Steel finishes

Tsuchime

Tsuchime finishing involves working the blade with a special hammer after forging. The hammer strikes grooves in the blade, making food stick less while cutting.

Tsuchime has become popular in recent years, mainly because of the unique look it gives a knife. Blacksmiths such as Yu Kurosaki and Nigara create custom hammers to give their knives an exceptional finish.

Kurouchi

Kurouchi is the black forging layer that forms while forging. In the last few decades, the blacksmiths had removed it by polishing the blade. But as knife collectors look for more authentic knives, blacksmiths are bringing back this finish.

The Kurouchi layer helps protect a knife from rust. The black finish does diminish with use, so don't expect the blade to stay that dark. It can also form a patina layer, giving each knife a unique color glow.

Nashiji

Nashiji is the Japanese word for the skin of a pear because the finish resembles the uneven texture that a pear has. The textured surface makes food stick less while cutting.

What the finish looks like depends on the blacksmith. Some smiths also leave the forging finish without polishing, making it a combination of Kurouchi and Nashiji. The Nashiji hides future scratches on a blade and gives it a rugged look.

Migaki

Migaki is the Japanese word for polished. A polished blade has the least resistance when cutting, but food can stick to it more. There are different types of polishing, from the misty Kasumi finish to the mirror polish (mirror-polish). One disadvantage of polished knives is that scratches and other imperfections are more likely to be visible.

These are the main techniques used to make a knife special. The difference in cutting is minimal, so choose what you like the most.

I would love to hear what your favorite finish is and why!