Japanese Layered Steel & Other Knife-Making Techniques.

June 06, 2019 4 min read 0 Comments

Japanese Layered Steel & Other Knife-Making Techniques.

De-mystifying the oft-confusing world of Japanese knife-making techniques.

We love Japanese knives. They’re sharper and they hold their edge for longer.

You may ask, “how do they do this?”

Because they’re made out of harder steel, of course! The steel your knife is made of is arguably the most important factor to consider when buying a knife. Soft steel, like what you’ll find in Arcos Products, is very durable, but can’t hold a razor sharp edge or perform like a Japanese blade. Imagine trying to slice a tomato with an axe. No fun.

That said, not all Japanese knives are created equal. There are many techniques blacksmiths and manufacturers take advantage of to achieve different results. Lets go over some of the different methods these guys use to achieve true slicing nirvana!

Diagram of San-mai, Nai-mai and Mono Construction

San-mai or three layer construction

By far, the most common type of knives you’ll see on our shelves aresan-mai knives. San-mai simply translates to “three layer”. It all stems from a pretty simple idea—the harder your steel is, the better your knife will hold its edge. This is a fact. As steel becomes harder—either through adding elements such as carbon, or by heat treating—the more fragile and brittle it can become. This can create a pretty serious problem. If you want your knife to stay sharp for a super long time, you need to make it hard, and therefore, brittle. San-mai construction solves this problem elegantly. By forge-welding softer steel onto either side of your hard steel, you give the blade a great deal more structural integrity without sacrificing its ability to hold an edge! If you look closely at the edge of your fancy Japanese knife, you might see a squiggly line. This is where the hard core-steel pokes out from in between two layers of soft cladding steel - like a slice of ham hanging over the edge of your sandwich.

Detail of San-mai construction on a Maskage YukiNot all blacksmiths produce san-mai knives using the same methodology, however. The Haruyuki Yokuma line, one of our favourite factory forged lines, takes advantage of some pretty sophisticated technology. They work with “pre-laminated” steel. They cut their knife shapes out of a large sheet of san-mai steel with a cookie cutter-like punch. While our pals at Moritaka Hamono, a family of blacksmiths who have been forging swords and knives for over 700 years, prefer to laminate their own steel together at their workshop.

Moritaka Hamono forged knifeInsead of steel cladding, the Moritakas actually clad their hard core steel in iron! There is no shortage of variety in san-mai knives. Some are made with two different stainless steels in both cladding and core, two types of carbon steel, or a combination of both. Some of my favourite knives are made with a super hard carbon steel core, and have stainless steel lamination to make maintenance easier, as carbon steel can rust if not properly cared for.

Fujiwara Maboroshi Santoku

Ni-mai or two layer construction

Most single bevel knives use a similar concept as the san-mai for protecting harder steel, but they’re typically made using a technique calledni-mai, which translates into “two layer”.  Single bevel knives share the same concept as san-mai knives—the hard and brittle steel does the cutting and a single layer of softer steel is forge-welded onto the face of the knife to keep it from being too fragile. Single bevel ni-mai knives are also sharpened and ground quite differently. The hard steel on the back of the blade is concave giving these knives a non stick quality.

Mono-bar construction

The honyaki method, the oldest of the old school, it’s amono-bar technique that has been used to make swords for hundreds of years. (If you’ve been paying attention, I bet you can guess what “mono-bar” means. Less than 1% of knives produced in Japan still use this time-honored technique, but the resulting blades are considered by many knife nerds to be the finest on the planet. There is too much to learn about honyaki knives to cover here, so Chris wrote them their own blog post to pay respect to these beauties. 

All this said, not all mono-bar steel knives are that fancy. As the name implies, these knives are made of a single type of steel, and it usually isn’t the hardest stuff around. The most basic method of mono-bar construction tends to create knives that areokay at holding an edge, but make up for their lesser edge-holding ability by being, by-far, the most durable Japanese knives available. The Tojiro Red Handle blades can take a bit of a beating, are easy to hone and sharpen, but aren’t able to hold an edge quite like most of our harder blades. Make no mistake—they’ll still hold a much keener edge than that set of 9 you bought at Canadian Tire for $23. And for not that much more cash. If you’re worried about your knife roll getting jacked because you’re working somewhere sketchy, these are absolutely the right knives for you!

Tojiro Red Handle So what’s the right choice? Which knife is the best? Well, it all depends on what you want it to do. At the end of the day, knives that are made out of the hardest steel hold a sharp edge the longest. San-mai, ni-mai, and honyaki knives are truly the most capable in this regard, but they may not always be the correct choice for the job. There’s no shortage of affordable san-mai knives, but if you’re going to be doing rough and tumble jobs like cutting through small bones or partially frozen food, they might be a bit too fragile and delicate. Honyaki knives are gorgeous and hard, but they are rare, and often have a much higher price tag, not a knife you want to leave at work unsupervised. Mono-bar knives are great at taking a beating, but they require more honing and sharpening overall, and they’ll never have that same bite as thinner blades.

I recommend having a good variety of tools in your arsenal that specialize at different jobs. You know what they say - If all you have is a hammer, everything looks like a nail. I use san-mai knives for everyday work, a single bevel ni-mai for fish, and my mono-bar Tojiro Red Handle honesuki when I’m butchering.

Owen Whitinger
Owen Whitinger

Owen is another ex-chef among our ranks. he has been Chef-ing in Edmonton for around 12 years but gave it up to be a human being again! An avid music lover, he plays guitar, loves Radiohead, and has probably been to about 500 concerts. Oh, and he can most definitely beat you in a game of Street Fighter. come chat with him about football, and steel!