The Japanese Gennou Hammer & Handle Part 10 – Laminated Gennou Heads

This image has an empty alt attribute; its file name is kosaburotansetsugennou.jpg

This image has an empty alt attribute; its file name is kosaburotansetsumei.jpeg — A modern-style (post 1890’s) gennou with high-carbon steel faces forge-welded to a soft jigane (low-carbon/no-carbon) iron body. You can see the difference in color between the soft jigane body and the hard high-carbon steel faces. This laminated construction was commonly used in Japan before inexpensive steel imported from England became available. The finish is hand-filed, and the blacksmith’s name, “Kosaburo,” meaning the “happy third son,” is hand-engraved. A high-quality gennou head is truly a lifetime tool. In fact, I have used this head hard as a professional and hobbyist for over 35 years, as you can tell from the dings and light corrosion. The handle is made from Japanese kurogaki wood (black persimmon, ebony genus), a rare variety valued for high-end cabinetry and casework in Japan. Kosaburo’s eyes are always as close to perfect as a man can forge them by hand, and better than all but a few expensive machines can manage.

Fast is fine, but accuracy is everything.
Wyatt Earp

n the previous post in this series we talked about the difference between mass-produced and hand-forged gennou heads. In this post we will take a look at a more antique style of gennou head.

A Laminated Gennou Head

Prior to the advent of inexpensive steel imported from England, gennou had bodies forged of soft low/no-carbon steel with wafers of hard, high-carbon steel forge-welded to each face. The shiny strips of steel called “Hachimaki,” meaning “ headband,” polished onto the sides of the ends of gennou heads sold nowadays, while purely decorative, are vestiges of this old-timey method.

The photos above are of a laminated gennou head hand-forged by Kosaburo which came to me long ago as payment for a debt. Laminated gennou heads made this way are still available today at exorbitant prices. I understand Hiroki occasionally makes a few.

Some believe the combination of hard face and soft body produces a softer impact and less vibration making the gennou less tiring to use. Others prefer the slightly different sound they imagine a laminated gennou head makes. I have used this laminated Kosaburo head for many years, and while I am very fond of it, I cannot detect any advantage to its laminated construction.

While laminated gennou are much more expensive to purchase, the blacksmiths I have spoken with have told me that they are significantly easier to make than one-piece high-carbon steel gennou since they do not require the more difficult differential hardening process. And they all agree that laminated construction provides no practical advantage to the end user. A curio in other words. Nothing wrong with that so long as one’s expectations are calibrated accordingly.

If you are just getting started in woodworking, or are on a tight budget, a quality mass-produced gennou head will do the job if you clean up the eye and replace the handle with one that fits your body.

Better yet, buy a hand-forged head by Hiroki or Kosaburo and make your own handle in the best craftsman tradition, and take pride in a custom tool of the highest possible quality that will serve you well for your entire life.

However, if you have the budget and enjoy collecting traditional tools, then by all means try a laminated gennou head. They are not easy to find nowadays.

YMHOS

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2 thoughts on “The Japanese Gennou Hammer & Handle Part 10 – Laminated Gennou Heads”

Very interesting! I suppose it would be worth a little money to have one’s hammer make a more pleasant noise all day. These days in the USA carpenters sing along with the radio in Spanish for acoustic entertainment, at least at the house being built next door.

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covingtonandsons says:

September 9, 2020 at 23:05

I’m not so sure it’s a more pleasant sound, just different.

Sounds like you’ve got some happy mariachi workers next door! Brings back pleasant memories of when I was an apprentice carpenter working summers in Las Vegas with a mostly Mexican crew. They were good men and kind to me. Do me a favor and take over some cold beers or soft drinks to them near the end of the day on Friday. I’ll pay you back.

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