By varying the carbon content and temperature of the forge, the smith can either add or remove carbon or oxygen from the steel to get the right carbon content in the finished blade (about 0.7 percent). I enjoyed reading about the tatara, or iron smelter, which wasn't invented in Japan but seems to have originated in Manchuria and then brought to Japan by way of China or Korea. It's during this phase that certain impurities such as sulphur are removed as slag and carbon is added to produce steel, although the resulting steel is still low quality as the distribution of carbon isn't uniform enough to produce a strong sword.

It was also fascinating to learn about how the hamon or temper line is created and made to appear (it marks the boundary between the hard martensite edge and the softer baenite), and the rediscovery of how to create the utsuri, which was highly prized on swords of the Bizen school but was lost for hundreds of years until just recently, and involves another change in the crystalline structure of the steel between the side and the back of the blade. I also learned how to appreciate the different crystal structures (nie and nioi) and textures that make up the appearance of the blade (jintetsu) and what to look for in a good sword. There is also a detailed discussion of the different types of hamon and which are preferred and prized.

Some of the details are humorous and ironic. I learned that a modern swordsmith can legally only make two swords a month. This is because the great smith Mayairi could only make two a month when they standardized on this more than half a century ago. But that's because Mayairi insisted on cutting up his charcoal by hand to make it uniformly fine with a scissors, which took up most of his time. Most smiths crush the charcoal and then use a sieve to select just the right size pieces for the forging process. But because Mayairi was the greatest smith of his time the law was based on his output and has never changed since. This has resulted in many smiths travelling to Taiwan or China to make extra swords for the export market during part of the year to increase their income, since they can't sell them in Japan.

There are also chapters on every phase of the sword-making process, including sharpening and polishing, the making of the habaki, the construction of the saya or scabbard and the other koshirae, or fittings such as the tsuba (guard), and so on. Just the polishing process itself can take two weeks and involve many different steps in terms of the sequence of polishing stones and polishing methods. Also almost all of the stones used are still natural, just like in the old days, some of which can cost thousands of dollars. Dozens of steps are involved as the polisher goes from the coarsest to the finest stones and to the final polishing of the sword. This is the phase during which the hamon can be brought out most strikingly, and the final lines of the sword defined. The polishing of the tip of the sword is a special step by itself, and the mune or back and the groove are actually burnished or rubbed rather than polished, using several different hardened, sharp needles.

The book begins with a brief history of the Japanese sword which covers the different types and styles and covering the characteristics of the five main schools of classical swordmaking, of which the Bizen and Soshu schools today are the most important and prized. The book is profusely illustrated with many photos and drawings of swords and the different aspects and features of the blades, and what they are called. All in all still a fine book on the Japanese sword which has become a modern classic.

I own Sato's "The Japanese Sword : A Comprehensive Guide" as well as Yumoto's "Samurai Sword a Handbook", and they are clearly not as complete as that one (esp. Sato's.)

"The Craft of the Japanese Sword" is amazing in that it has a large number of extremely clear B&W pictures. Those are clear enough to show examples of the steel's grain, of what an utsuri looks like, of what makes nie different from nioi, of the appearance of the hamon at each stage of the polishing, etc. The clarity & quantity of the pictures is the main asset of this book to the katana enthusiast, be they interested in modern or antique swords, made in Japan or not.

The book is also great because of the info it provides on all the stages before the blade is forged (i.e., how to obtain the necessary steel ingot, or tamahagane) and after it is forged (polishing, of course, but also the craft of the scabbard, of the fittings, etc...)

This is a super dense book, packed with info, where not a single line is wasted. I cannot recommend it enough to anyone interested in the Japanese swords, be they swordsmiths, martial artists, or collectors. The book is geared toward the swordsmiths but provide so much info that a martial artist or collector planning to invest into a fine blade should absolutely read that book. This will prevent many a disappointment...