How to Select an Oil Prefinish for Shou Sugi Ban Siding

Read: Part 1: How to Select a Shou Sugi Ban Surface for Your Project

Last week we covered the first step in selecting shou sugi ban siding for your project–choosing a surface type. Once you make that decision, it’s time to select an oil prefinish. This will determine the overall color, tone and sheen of your siding as well as make it more durable. It is critical to note that the shou sugi ban charring technology was developed for better durability without an oil finish. However, read on to understand why most people choose to have an oil finish applied to their shou sugi ban.

Overview of Oil Prefinishes

Oil finishes have three functions in our world: to match the wood color to your design vision, to slow down color weathering and fading over time, and to seal in soot from the burning process. There have been dramatic changes in oil formulations over the past 20 years, with traditional monomer oils replaced with high-urethane formulations, solvent carriers replaced with water carriers, and various longevity enhancers such as reflective silicone. Different pigment colors have gone in and out of fashion as well, such as reddish pigments popular in the 1990’s having since gone out of style in favor of more blacks, grays and browns today.

A major factor in wood longevity is UV protection, because shou sugi ban will eventually wear out after 80-150 years due to surface wood fiber UV degradation and plank thickness erosion. All oil finishes offer at least 95% UV protection simply from dried oil residue on the wood surface so will protect the wood from UV exposure and increase the siding’s lifespan. Exterior grade oil finishes have visible and invisible pigments that bring this up to near 100% since pigments are the main ingredient in oils for UV protection.

Higher UV protection results in delayed weathering of the wood fibers, but at the sacrifice of the oil finish. Therefore siding has re-oiling as a periodic maintenance. The more re-oiling maintenance done over the siding’s lifetime, the longer it will last.

Nakamoto Forestry’s Oil Prefinish Options

Depending on the wood surface selected, you may have multiple oil formula options available. Formulas generally fall into one of two categories: traditional oils or waterborne oils. Traditional oils are monomers that oxidize into a polymer after application. Waterborne oils are basically halfway between an oil and a paint. Traditional oils are semi-transparent and will fade in color gradually as they weather. Waterborne oils will often stay the same pigment color until the oil erodes off the wall.

We offer both traditional linseed and waterborne alkyd oils for these two categories. We make all of our formulas from oil pressed from plant seeds such as linseed, tung, and soybean. It is recommended that customers don’t think about this too much. Simply choose whichever sample swatch or product photo you think is the best fit!

Oil Colors by Surface

We offer four different surface options for wood siding. Unburned Sugi cypress, traditional charred Suyaki, brushed Gendai, and twice-brushed Pika-Pika. Depending on which surface is chosen, various color options are available.


Suyaki is only available in black, with the two different oil prefinish options dependent on whether or not it will be installed on the exterior or interior. If you’re looking for a traditional, textured black look, you can’t go wrong with Suyaki!


Gendai is naturally a rich brown color, with the charred grain slightly peeking out from the surface. It is available in a range of blacks, browns, greys and white, and usually matches to any siding project without issue. Gendai™ with Black oil prefinish has been our most popular selling product for several years, both in Japan and North America. Not so much because it makes a unique statement, it simply looks really good for a long time.


Pika-Pika is wire-brushed and has the lightest natural tone out of our charred wood products. It has a pronounced grain pattern that can be stained with an oil finish to a variety of different colors.

Selecting an Oil Prefinish

Once you’ve narrowed your shou sugi ban options down by surface, you can begin to decide which color of siding you’d like. Our team is very experienced with guiding customers to the right options based on project details, so please don’t hesitate to give us a call regardless of where you are in the decision making process. The most effective way to compare colors and surfaces is to order product samples, available here. Choose the formula and color you like best since all Nakamoto Forestry shou sugi ban products will last a lifetime.

1 Comment

  • Jason Banks says:

    I love your products an the variety of options. I am interested in doing the first floor of my home in your product. Can I run shiplap vertically or would that invite water intrusion? Also do you have a catalog to send me? Thank you and have aa good day.

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