The Japanese Gennou & Handle Part 11 – Decorative Gennou Heads

Simplicity is the ultimate sophistication.

Leonardo Da Vinci

In the previous post in this series about the Japanese gennou hammer we looked at an old-fashioned laminated gennou with some simple surface decoration and discussed its construction and benefits.

In this post we will take a gander at some other styles of expensive heads with decoration for the sake of being decorative.

Decorative Gennou Heads

A chemically-blackened square head by Masayuki with his name engraved in red characters

For a higher price, more decorative gennou can be had. Some of these have various surface textures and applied finishes, while others have designs etched into their surfaces, with the more expensive varieties even have designs of dragons, tigers, zodiac and religious figures deeply hand-engraved into their surfaces.

A “suminagashi” pattern-laminated octagonal head by Masayuki
Hand engraved images of the gods of wind and lightning. Despite the polished hachimaki strip, these are not laminated heads.

One of my favorite gennou is an 80monme square head with the figure of a monkey acid-etched on one side and some Chinese characters on the other referring to the patron god of those born in the Year of the Monkey, which I am. Sorry, I don’t have the hammer with me here in Tokyo, so no pictures. It was a gift from my Japanese Mother-in-Law (RIP) and so I value it highly although I don’t use it anymore.

She had it blessed by a Shinto Priest at the same time he came to perform the annual blessing of their book-binding factory in Sendai, so I consider it more of a good-luck charm than a working tool. It has not aged gracefully.

BTW, it’s not at all unusual for carpenters, construction companies and factories to have Shinto Priests perform similar ceremonies at least once a year to purify their tools and equipment and to bless their workplaces for safety purposes. Both of the large construction companies I worked for in Japan had Shinto “Kamidana” shrines in their offices and smaller ones installed at their major jobsites to encourage deities and local spirits to protect the jobsite, people and tools, and to drive off malevolent spirits that might cause harm.

Construction companies in Japan are especially old-fashioned this way. One large construction company I worked for in Japan was established 147 years ago, just a youngster by Japanese standards. Perhaps the oldest construction company in Japan is Kongo Gumi Co., Ltd. established in the year 578 AD. Other large and old Japanese construction companies include Kajima Corporation, established in 1840, Shimizu Corporation, established in 1804, and Takenaka Corporation, established in 1610. Long memories and deep traditions.

A typical kamidana shrine in an office.

Of course, decorating a gennou head adds nothing to its functionality while significantly increasing cost, so highly-decorated heads are probably more suitable for ceremonial purposes, for displaying in a collection, or as gifts rather than practical tools. In fact, the older generation of Japanese craftsmen I learned from, now all either in their late 80’s and retired, or passed on to the big lumberyard in the sky, considered such decorated tools frippery beneath the dignity of a respectable “shokunin” (a wabi sabi sorta thing) and would mercilessly rib someone who brought a gaudy tool to the jobsite or workshop.

Aging Gracefully

If you are considering purchasing a decorative gennou head, one factor you should seriously consider is the appearance of the head after many years of use. After all, a quality gennou head should be a lifetime investment and an heirloom tool. It may look as beautiful as Raquel in her fur bikini when new but will it look better than my scratched and rusty etched zodiac monkey head after 20 years of use?

A “suminagashi” pattern-laminated square head by Masayuki

Some heads pictured in this article show a pattern-welded structure known as “Damascus” in the West, or “Suminagashi,” meaning “ flowing ink” in Japan. This structure is not the famous Damascus steel developed in the Levant centuries ago and made famous by swordsmiths. It is simply a mix of at least two different types of steel, one of which resists oxidation/discoloration when exposed to an acid wash, creating the difference in color. Theoretically, this construction neither improves nor harms the performance of the steel so long as the deferential hardening process is handled properly, but personally, while it looks fun, I distrust this material for gennou heads and blades that must do real work.

Hand-engraved dragon

Other heads have received fancy decorative surface treatments that neither harm nor improve a hammer’s performance. However, being decorative, one should consider the durability of such treatments. Chrome, nickel or copper plating, for instance, will not remain unchanged long in the case of a hammer used frequently on the jobsite or if laid on the concrete floor of a workshop frequently. Color case hardening, pickled finishes, paint, and even most bluing will look nasty and may rust before too long.

Perhaps the most durable surface finish is the black oxide that forms naturally on the steel surface during the heat-treatment process because it is reasonably rust resistant and naturally harder than the steel/iron it covers. It’s my favorite, but for some reason doesn’t seem to attract the ladies. Bummer. Decisions, decisions…


Raquel Welsh wearing her iconic fuzzy bikini in the 1966 film that made her an international sex symbol “One Million Years B.C.

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Previous Posts in The Japanese Gennou & Handle Series

6 thoughts on “The Japanese Gennou & Handle Part 11 – Decorative Gennou Heads

  1. For a long time, I considered decorative genno heads a distraction. I have since managed to let go of many of my presumptuous attitudes, and learned to appreciate all craftsmanship for what it simply is. I still prefer a ‘plain’ and subdued aesthetic but I own two mokume/suminagashi heads and they are in no way inferior to my regular genno. In fact, I enjoy using them, and quite a lot.


    1. I disagree that not being fond of decorated gennou heads is in any way “presumptuous.” It is simply preference for a different type of craftsmanship that produces a different type of appearance.

      The problem, as I see it, occurs when people pay a high price for that decorative craftsmanship (some examples cost thousands of US dollars) expecting better performance only to be disappointed when the performance is not superior, and the appearance they paid so much for deteriorates with time and use, as does all external decoration. If they make the purchase fully realizing that a case-colored gennou head or bright chisel blade hand-engraved with twined dragons will not perform better than a standard one, and indeed may look significantly worse after a dozen years of hard use, and may even cause them to be seen as silly by some professionals, then they got what they paid for and can justifiably complain to no one.

      While we do sell a few rare collector’s tools at C&S Tools, our primary target market is professional craftsmen who want maximum long-term performance at minimum cost. Suminagashi chisels and acid-etched gennou don’t fit in.

      We encourage everyone to express themselves through their tools and find joy in using them and the things they make from wood with them, but we don’t want to actively encourage people to purchase tools that may disappoint. Therefore, while this blog posts contains pictures of fancy heads, we don’t sell them, nor do we encourage our customers to buy them, even though we could easily profit from such sales.


  2. No, I understood your position right off the bat, and I wholeheartedly applaud your motivation. It comes through strongly and consistently in all your posts.

    I was referring to myself. When I was young, my motivations weren’t always as noble. One of the wonderful aspects of journeying through life – and craft – is the ability to reflect back on our former self. That’s all…

    Liked by 1 person

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