Is a Japanese Polishing Plane Better Than a Western Smoothing Plane?

While doing some research on wood finishing, I came across an article praising wood planes from the far off country of Japan. I was intrigued. This article enumerated some interesting points. One of which I wanted to address here. The Japanese Polishing plane is objectively better than the Western Smoothing plane.

For the skilled woodworker, the Japanese polishing plane is better than the Western smoothing plane, because the Japanese smoothing plane produces a more finished surface directly without the need for addition finishing(sandpaper). The polishing plane does this with a high angle blade. This allows the blade to maintain its edge and perform well even with hard and oddly grained wood. While expert results are possible with Western smoothing planes, Japanese polishing planes, also known as kannas, offer more precise and—yes, literally—polished results. 

Just like with most artistry, there are differences in technique and tools for different individuals, cultures and regions. Some artisans may prefer one particular technique or tool over the other for sentimental reasons or other bias influences. However, when considering specific criteria, one tool or method may be objectively verified as superior for everyone.

In the case of the comparison between Western and Japanese hand planes for woodworking, this article votes that the Japanese polishing plane is a better option. We take this position because polishing plane produces more aesthetically pleasing wooden surfaces by both Western and Japanese standards without the need for additional sanding. The following article offers details and context to support that argument.

 

The Purpose of Japanese Polishing Planes and Western Smoothing Planes

Traditional carpentry can be a long process. If your final product product requires a smooth finish, it may involve the use of specialized hand tools.  Within the Western world, there are five main hand planes used in the process of leveling and finishing. The five are known as: jack planes, joiner planes, block planes, rabbit plane, and smoothing planes. A smoothing plane, like the polishing plane, is the final step for tool finishing. Both have the smoothest end result and remove most, if not all, of the previous tool marks.

Wood Planes vs Metal Planes

Western woodworking planes span the gambit from metal to wood. If you were to take a quick census however, the most common material used for the body is ductile cast iron. These type of planes are cheap and easy to produce and with some quality machining and care will hold a level surface almost indefinitely. High quality planes can also be found in brass or even bronze. While more expensive, these materials make the plane heavier and resistant to corrosion. The weight helps to carry the blade of the plane through uneven material.

Note: The size of all planes will vary greatly, however, wooden planes are generally thicker, since they need to provide the structure to securely hold the blade and chip breaker. I would also argue that wooden planes, generally require more expertise to maintain. In my experience they are less forgiving of mistakes and require a lot more fine tuning to obtain the result you are looking for.

Kannas, one the other hand, also come in different sizes and degrees of quality but have one defining feature; they are all made of wood. Even after a fair Google search, ‘metal Japanese polishing planes’ only yielded more wooden examples. Unsurprisingly, some models of western wooden smoothing planes closely resemble a Japanese kanna.

Why is Metal Preferred over Wood?

According to Paul Sellers’ blog, “A Lifestyle Woodworker”, Western woodworkers prefer metal planes, because they are easier to adjust mid-project. Both metal and wood planes succumb to the friction which alters their precision. Since metal planes are so thin, they can be slightly bent in order to correct them. Wooden planes must be filed which takes more time to do correctly.

The Different Parts and Functions of a Smoothing Plane and a Kanna

Conceptually, the smoothing plane and kanna are quite similar. Both the smoothing plane and the kanna include a flat surface, or sole, at the bottom with a narrow hole, called a mouth, roughly through the center of the plane. The blade makes an acute angle with the surface being smoothed and polished. The axis of the acute angle is in the same direction that the plane moves. The blade that cuts away the imperfections of the wood one paper-thin layer at a time. The implementation of this cut is where things begin to differ. The western plane is further broken down into a frog(J), an iron/blade(B), a chip breaker(F) and a lever cap(C). See the picture below. More description can be found on Wikipedia.

Kannas have fewer parts and rely on friction and pinching the blade to keep it in place. The primary blade of kannas are crafted differently than the primary blades of the smoothing planes. Kannas’ blades are heavier and thicker and the polishing plane is even more so. These are adjusted before planing, by taping on the plane itself. This blade is the main difference between the polishing and smoothing planes. With a blade angle of over 60º the polishing plane acts as almost a scraper.

The final large difference is in handling. To be more specific, kannas do not have handles. Rather, the woodworker holds a wooden block which houses the cutting blade. The woodworker holds the wooden block itself when pulling a kana across a surface. Western smoothing planes include a wooden or metal handle attached to a flat metal surface, the plane. Woodworkers use the handle to repeatedly push or pull the smoothing plane across the wooden surface that is being smoothed.

What is Burnishing? How does it Vary Between Smoothing and Polishing Planes?

An integral part of a smoothing plane’s process is burnishing. Burnishing is when the surface of the smoothing plane continues to rub against the surface of the wood after it has been shaved by the blade.

While generally thought to be a positive aspect of planing, burnishing is defined as a polishing process accomplished by rubbing with metal. A kana does not burnish wood as extensively as a smoothing plane. The difference in contact of a smoothing plane and a kanna offers another reason why they perform differently.

When set-up and handled correctly, a kanna is designed to only make contact with the wood towards the front and back of the plane. A kannas’ plane surface is slightly concave. This is different from the smoothing plane whose plane surface must be completely level and flat.

When is a Smoothing Plane Better than a Kanna?

A kanna is not ideal for beginning woodworkers who want to start immediately. To use a kanna successfully, a woodworker must be skilled in knowing how to navigate the woodworking process. A woodworker must know how to adjust the plane. This adjustment requires far more expertise than a smoothing plane.

When is a Kanna Better than a Smoothing Plane?

Basically when a woodworker is trying to obtain the smoothest finish possible. Now of course it is more complicated than that, but the results will speak for themselves. Practice taking cuts with the plane on scrap wood and adjust as you go. After some work you should be able to obtain a quality finish.

The blade of the kanna has a steep angle which means that the woodworker will not need to sharpen the blade as often. Beginners can focus on adjusting the plane and worry about sharpening skills at a later date.

Lastly, the design of the kanna elicits a motion from the user that is much more ergonomic for the body. The pulling motion associated with a kanna requires less effort from the arms and more effort from the legs which allows for a more fluid motion and less fatigue overall.

In Summary…

When skill level is not an issue, the kanna accels as the best option when choosing a hand plane to finish a wooden surface. The kanna produces better results and is more ergonomic.

Western smoothing planes may produce some sheen but they leave a more matte finish than Japanese smoothing planes. Thus, Japanese polishing planes outperform smoothing planes by producing undeniably more polished surfaces.  You can always add scrapping the wood as a last step to emulate the qualities of the Japanese polishing plane.

The kanna is more ergonomic. Japanese polishing planes require a pulling motion and puts less strain on the body than the pushing motion required for smoothing planes. The design of high-quality kannas also supply woodworkers with heavier, sharper blades. The combination of better working conditions and better quality provide experienced woodworkers with an overall better experience.

If you are a beginning woodworker, Western smoothing planes allow you to start right away and get decent results. But as you become familiar with the woodworking process, consider practicing with a kanna.

If you are a skilled woodworker and you only use Western tools, incorporating a kanna might be worth a try. What’s most important is knowing your options as a woodworker so you can decide what works be for you.

Other Interesting Tips for Kannas and Smoothing Planes

  • When sharpening a blade for a kanna or a soothing plane, sharpen until you cannot see light reflected off on the very edge of the blade. A sharp blade will have its two edges come together cleanly with no burr. A burr will reflect the light.
  • Use the entire water stone when sharpening a blade for a smoothing plane, this will ensure that your stone remains level and will allow you to sharpen confidently with the same stone for longer.
  • Learn how to sharpen by hand. It will be more difficult in the beginning, but with practice it will become easier. Sharpening by hand is faster and more accurate.
  • Allow your kanna to get acclimated to its environment before adjusting its wooden block plane extensively. Wood expands and contracts. If you adjust a kanna too soon, it may change more on its own after you’ve adjust it.
  • Whether using a Japanese polishing plane or a Western smoothing plane, enjoy the process of creating with your hands!

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