What you are getting yourself into:
- ~ 1,800 words
- 6-8 minutes reading time
- 8 pictures
- <1% sarcasm
I have been asked numerous times over the last few years about uzukuri on my Instagram channel – probably more so than about any other technique. This post will hopefully help give some context and clear the confusion about this humble tool. From a purely egocentric perspective, it should also hopefully save me some time in answering the same questions directly, over and over again.
For clarity, the word uzukuri refers to both, the tool, and the finish created with the tool. I will use the term uzukuri on its own to refer to the tool and uzukuri finish (uzukuri shiage) to refer to, well, the finish.
What is uzukuri, then?
In the woodworking hand tool context, uzukuri are stiff brushes made of tightly bound fibres of organic origin. Thanks to the use of different fibre materials, they come in 3 levels of fineness.
The rough grade and most commonly used uzukuri are made of dried Karukaya – the Japanese variety of themeda triandra grass species, known in Australia as kangaroo grass. The same material is used in the production of brushes intended for scrubbing kitchen pots and pans in Japan, but those are usually wound in a much looser fashion than the woodworking tool is.
The medium grade uzukuri is made with hemp fibres and the fine grade is traditionally horse hair fibre.
How, and why do you use uzukuri?
The primary application of uzukuri treatment aims at creating a textured and/or polished wood surface. As you rub the workpiece back and forth with the rough brush, the wood fibres in the lower density, soft grain aspect (earlywood in most species of timber) are gradually removed. The higher density, hard grain aspect (usually latewood) is also getting worn at least to some extent, but at a much, much slower pace. As a result, you raise the hard aspect of the grain and, in effect, accentuate the grain in the workpiece, 3-dimensionally.
The undulating surface that this technique creates is not too dissimilar in texture from a surface worn by prolonged exposure to the elements.
Another traditional application of uzukuri is a complete or partial removal of a finish such as paint or lacquer, or of stain. Again, this can be used to create an impression of an aged surface. If you are trying to blend a repair into an old piece while maintaining and matching its existing patina, uzukuri may give a convincing effect, and I have seen it used in such scenarios. Personally, I do not have experience or interest in this type of work so I will leave it at that.
Finally, I feel obliged to add that wood panel and floor board suppliers and installers in Japan may sometimes offer uzukuri finish on the boards; this finish will be produced by machine, usually with nylon brushes. Here’s an example from this Fukuoka-based company’s website.
Is it really a finish??
Even though for many Western woodworkers anything short of several layers of nuclear-grade polyurethane is unworthy of being called a finish, uzukuri finish is in principle just this: a brushed and polished wood grain surface. By raising the hard grain aspect, however, you do ensure that in future use, the contact with the surface of your piece will be mostly on said hard grain aspect. Since that exposed, dense aspect of the grain will wear much slower, you do end up with a more robust surface overall.
In other words, uzukuri shiage plays to the strengths and qualities inherent in the material. It also creates a very tactile surface that will age beautifully. It is not intended to compete with modern chemical finishes like polyurethane; it is a completely different approach and philosophy.
Whatever, can I still slap some poly on?
*sigh*. OK. Applying a film-building finish over uzukuri-treated wood surface is likely beyond the jurisdiction of most criminal courts, but I personally can’t see why you would bother doing uzukuri in the first place, then. The wet finish will tend to fill the ‘valleys’ of soft grain aspect and the film, as you build it up in subsequent coats, will negate the tactile qualities you so painstakingly created with uzukuri. I have to say that I have once or twice used a coat of finishing oil over uzukuri. Not a film-building finish, however.
Some Japanese craftsmen pair uzukuri with ibota (shellac wax). Typically, a bar of wax will be rubbed into the grain, or the brush will be dipped in powdered ibota, before working the surface thoroughly with the uzukuri. I would repeat these two simple steps at least a couple of times before progressing to the finer grades of uzukuri if required. And although, again, some will baulk at the idea of even calling wax a finish, the result when paired with heavy brushing into the grain is surprisingly long-lasting. More so than just rubbing some wax on with a cloth. As grandma used to say, don’t diss what you haven’t tried.
Incidentally, if you are into Japanese sword making, you may be familiar with the method of applying ibota powder to samekawa (the shark skin layer in the handle). This is accomplished with uzukuri as well.
As it happens, uzukuri may also be used in the process of creating other, slightly more complex finishes like tonoko, but we are focusing on the simple uzukuri finish itself here.
OK, you made a lot of noise and I see you mentioned wax. What about Roubo’s polissoir, then? How is it different?
Ah yes. In the past few years, the mostly forgotten and humble polissoir, and its related wax finish, have been brought into the awareness of the Western woodworking community – at least those parts of the community who are oriented towards traditional techniques and hand tool woodworking. Much of this very quiet revival has been through the efforts of Christopher Schwarz and Don Williams.
We know that the polissoir (from French: polisher) was a popular tool in the 18th century – at the very least in France. Andre Jacob Roubo in his eponymous “l’Art du menuisier” gives us a glimpse into the form and function:
The polisher, figures 8 & 9, is a sheaf of ordinary grass or straw, about 4 thumbs long, by about 2 thumbs in diameter. This sheaf is bound tightly along its length. Before making use of it, one soaks it in molten wax, which one lets cool, after which one rubs the polish on a piece of wood to smooth it and make it proper to polish the work.Andre Jacob Roubo, ‘l’Art du Menuisier’
There are 4 main points of comparison between uzukuri and the polissoir that stand out to me.
- I feel, first of all, that both the uzukuri and the polissoir are simple enough tools that share a lot of similarity. I also feel the polissoirs that I have seen available commercially (like the ones made by Don Williams), seem very much close to the roughest – and most commonly used – grade of uzukuri. I understand said polissoirs are made of dried broomcorn (Sorghum bicolor) stalk material.
- One main difference, and one which should be obvious to any attentive reader by now, is that uzukuri come in three grades of fineness, achieved through the use of different fibre materials. A full progression from rough through medium to fine uzukuri, or a partial progression through any two grades, allows for some control and refinement of the work surface, if required.
- As mentioned above, uzukuri can be used with ibota – on the surface (!), just like in the polissoir wax finish. However, it is the texturing – raising of the hard grain aspect – that defines uzukuri finish. In other words, the polissoir is an implement one uses to apply wax and polish the wax finish. Uzukuri is a tool for raising and polishing of the hard grain aspect of the wood, which may or may not be enhanced with the use of wax.
- Unlike the polissoirs I have seen, uzukuri are bound with longevity in mind. As the bristles wear and shorten, a pull on the binding string will expose more of the bristles to be used. A very simple but clever design.
A final note to the perfectionist
If you are the kind of person who is used to checking their kanna finish with raking light (as you should be!), and you are new to uzukuri, knicker-twisting shocks may await as you inspect the wood surface.
As you start applying rough uzukuri on softwoods or very soft hardwoods, you will notice that the brush leaves more or less obvious scratch marks that stand out from the undulating grain surface. A fork in the road ahead will form. Either you embrace these marks as part of the process, or you do your sweatiest best to blend them in as the whole surface is worked through. It may be a comforting thought that further treatment of the surface with medium and fine uzukuri would allow you to refine the surface to some degree, but true perfection will likely prove elusive.
The main point, in case it is not obvious, is that this is a very different finish from an immaculate kanna shiage, or even from any flat-sanded film finish. That is the whole point. How much of the tool marks will remain is partly up to you, and partly down to the wood species. In really dense hardwoods individual scratch marks are a non-issue in my practical experience.
Personally, I very much enjoy the extra dimensionality that uzukuri finish brings to my work. My preference is to use it judiciously – for example, to selectively apply textural contrast. Should you wish to follow, you will be rewarded with an enriched repertoire of techniques available to you as a designer and maker.