26 Herramientas japonesas para trabajar la madera

A man in love is incomplete until he has married. Then he’s finished.

– Zsa Zsa Gabor

This is the last article in our series about designing and making a handle for a Japanese gennou hammer.

In previous articles in this series Beloved Customer completed designing, shaping and fitting the handle of your gennou hammer and attached the head. Then you tested it and perhaps made adjustments. Assuming Beloved Customer is satisfied with the results of those adjustments, at least for now, the time has come to sand it and apply a finish.

Finishing Options

There are a couple of approaches your humble servant might propose on the subject of finishing tool handles. The first is perhaps the oldest, and easiest, and that’s to do nothing. After all, tools are made for hands not museums, and flashy finishes too often make otherwise workmanlike tools look silly.

In addition, most woods (except for those that might cause allergic reactions) perform just fine unfinished, thankee kindly. In this “au natural” approach, you may choose to leave tool marks on the surface of the handle without sanding them into oblivion, lending your handle undeniable gravitas and dignity, even character.

An unsealed, unfinished handle will, however, unavoidably become stained and discolored, and it’s head may not stay attached as long as a well-sealed, well-finished handle. I say this from experience.

A good light-duty finish material for an au-natural handle is a quality non-slip floor paste wax like Johnson’s well-known product in the yellow metal can. Does it seal the wood? No, but it does help keep the handle looking cleaner. Why floor paste wax? Some waxes, for instance those used to polish furniture and automobile paint, are intended to provide a slick surface that encourages water to run off and to which dirt doesn’t adhere well. History has shown that slippery waxes used on floors will result in slips, falls, and a transfer of wealth to the legal profession. For the same reason, carnuba automotive wax is not ideal for tool handles, while non-slip floor wax is.

And then there are the chemical finishes such as linseed oil (BLO), milk finish, tung oil, shellac, varnish, lacquer, polyurethane, etc. To one degree or another, these chemicals tend to seal the wood reducing the penetration of dirt and oil, and (sometimes) slowing the movement of moisture into and out of the wood.

But what chemical finish is best suited to a gennou handle? It is far beyond the scope of this humble scribble to properly describe, much less evaluate, the many varieties of finish applied to wood, so I will simply provide a few comments.

Linseed oil and BLO, a by-product of the flax plant, are organic materials used for centuries if not millennia as a traditional finish in Europe. It was once used widely for paint and, until it was replaced by rubber and later petroleum products, flooring and waterproofing materials. Have you heard of “linoleum?” Of course, this was back in the day when lead was a common ingredient in paint and makeup. Linseed oil no longer has any value as a finishing material for wood because it never really dries without adding problematic, even toxic, chemicals called “driers,” it seals poorly, collects dirt, and discolors badly over time. But because it’s constantly mentioned in old writings, which many people trust just because they are old, linseed oil products are still in-use today. To advocates of linseed oil products I say “make sure you soak your oily rags in water and dry them outside well away from any fuel (like your house).”

I am a fan of the modern milk paints, but do not like it for tool handles. Nonetheless, it’s a valid option.

Tung oil is an ancient finish, but the price nowadays far exceeds its value, assuming you can even find an unadulterated source.

Shellac creates a beautiful surface coating but it’s far too delicate for tool handles.

Standard synthetic varnish, nitrocellulose lacquer, urethane and polyurethane are readily available, easy to use and can create a beautiful, durable finish, but when used in the traditional manner, the surface film coating they produce eventually chips and cracks with time, exposure to ultraviolet light, and expansion and contraction of the wood to which they have been applied. And every scratch accelerates this degradation.

Why is degradation of film finishes the a problem you say? The obvious downside of a once beautiful finish looking ratty aside, every defect in a surface film finish promotes the movement of moisture into and out of the wood, and of course increases the swelling and shrinkage of the wood it’s intended to protect. What most people don’t realize is that, as time goes by, the solvents and compounds in film finishes intended to provide flexibility in dealing with expansion and contraction of the wood dissipate causing the finish to gradually become more brittle, and break down and crack at a ever-increasing rate, independent of dings and other defects.

In modern times, the use of latex rubber in water-based paints has greatly reduced this problem, but such paints are not especially durable as a tool handle finish.

Sanding

If the au-naturel approach appeals to you, I recommend erasing marks left by files and rasps and replacing them with crisp marks and cleanly cut surfaces left by sharp edged tools like knives, carving tools, and spokeshaves. Unless a chemical sealer/finish material is applied afterward, a plain sanded finish is probably the worst surface treatment possible, whereas a surface cleaned with sharp blades will serve you better. I often use this texture for the endgrain butts of my hammers and saws.

If, on the other hand, you prefer a smoother finish, and are prepared to apply a chemical finish, then by all means sand away. But please do not sand the tenon. If you decide to sand the handle before installing the head, please apply masking tape protection to the tenon.

How fine should you sand your handle? I think 600 grit is fine enough, but I’ve gone as high as 1200 grit on fine-grained, hard woods like black persimmon. Did using such fine sandpaper make a difference? Nah.

After you’ve sanded the surface to where you like it, the next job is to eliminate hidden hairs. No, this does not involve applying hot wax to delicate areas of the body and then violently ripping out body hair so that you look delightfully-sleek in your new sequin string bikini, but rather it’s the job of encouraging the naughty ends of wood fibers still connected to the handle, but currently pressed flat onto and into the handle’s surface, to stand up so we can cut them off using sandpaper.

Dealing with these fiber is always important when finishing wood because, with time and moisture, they may pop up over time creating rough patches in the finish encouraging degradation. Once they are standing and no longer hidden, we can cut them off at the base with sandpaper to create a durable, smooth surface long-term even when exposed to moisture and sweat.

Although it’s not used much nowadays, sanding sealer was originally a shellac product developed specifically for this purpose.

To raise hairs, lightly wet the handle’s surface (but never the tenon) with water and allow it to dry completely. Some hasty people like to dry the wood quickly with a forced-air blower or even propane torch at this point to make any loose fibers stand up immediately in preparation for the next sanding pass. But simply allowing the wood to dry naturally is effective too.

This is an ancient, very effective technique. Please do this at least twice, after which you can apply the finish material.

Kanō *Hōgai,* Two_Dragons_in_Clouds (1885), ink on paper. Philadelphia Museum of Art. Father and son dragons are depicted playing in the clouds.

The London Finish

There’s a durable wood finishing technique I learned from custom gunstock makers that I wrote about in an earlier article about handplanes called the London Finish. This is the finish I recommend for hammer handles too. It can be as subtle or as flashy as you like.

A pretty handle is nice, but the key objectives for applying a finish to your gennou handle should be (1) to moderate swelling and shrinking of the tenon during seasonal and climactic changes in humidity; and (2) to prevent oil and dirt from penetrating the wood making it look grubby. This matters because such swelling and shrinking can cause the head of your gennou to loosen and do naughty, acrobatic stuff at inconvenient times. And a greasy, dirty handle is no way to treat a friend.

If the head is attached when applying the chemical finish of your choice (I recommend it be so), please tape it well to keep finish off the metal. Apply masking tape to the hammer head on all four sides of the eye, but leave the end of the wooden tenon exposed.

Tape the rest of the head well with masking tape.

Soak the finish material (flat varnish or polyurethane thinned 100% with high-quality thinner) into the eye and the butt as deeply and thoroughly as possible. Plan for three or four applications allowing time for the material to soak in and dry.

Do no use low VOC thinners as they contain politically-correct compounds of water, acetone, emulsifiers and other counterproductive substances the State of California’s poorly-educated but thoroughly-conflicted and richly-corrupt lawyers have determined will save the polar bears, but that will weaken the finish.

If you faceted the butt and want to keep it that way, you must be careful when sanding it or the facets will disappear. This is a matter of personal preference.

Of course, be sure to apply lots of finish to other surfaces of the handle, and wet sand them well as described in the article linked to above. Don’t allow a surface film to dry except for the first time as described in the webpage linked to above.

Hammers are lifelong tools, but too often handles are not. You can help your gennou’s head stay tight longer, stay cleaner, and look better longer by applying a London Finish instead of a thick surface film finish.

YMHOS

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A list of our gennou heads: C&S Tools – Gennou Hammer Head Pricelists & Photos