Josh Brower uses the shou sugi ban wood burning technique to make the two tablets
When shou sugi ban is mentioned in woodworking circles, it usually means a blackened, charred finish on the outside of the wood. In recent years, the look has caught on for both interior furnishings and exterior treatments for contemporary homes.
However, the term shou sugi ban is not known in Japan and is a Western phrase used to describe the process of burning and charring the wood instead of the final result. Some believe it is a mistranslation of the Japanese character for ‘yakisugi’, which is the final product after charring and brushing and translates to ‘charred cypress board’. Sugi is the term for Japanese cedar or cypress. Shou sugi ban and yakisugi are frequently used interchangeably, but they are not the same. Shou sugi ban is the process of burning the wood, and yakisugi is the finished result with no brushing.
Japanese cypress is the preferred wood for use in Japan and is typically used for siding. The burning technique makes the material resistant to moisture, UV, fungi and, of course, future fires. Pests do not enjoy the taste and will not chew holes through it, and it looks beautiful, which has inspired many copycat pieces today that are achieved using a chemical process instead of burning. Depending on how many brushings it is given after the original charred finish is applied, it gets different names and is sold at different prices on the commercial retail market. Nakamoto Forestry, in Portland, Oregon, breaks up the brushings into its own trademarked names, and states:
‘Gendai (brushed once) is the most commonly specified shou sugi ban “yakisugi” surface for exterior applications. A light brushing process knocks down the heavy soot and leaves a smooth, silky appearance. The burnt fibre crevasse shadows are subtle, and Gendai can either be installed with or without an oil prefinish. ‘Pika-Pika (brushed twice) is made by passing the shou sugi ban planks through a second wire-brushing process that removes all loose soot from the softer spring growth rings and leaves the late wood as contrasting burnt ridges. It is a topographic, textured surface that follows the wood grain.’
The traditional Japanese method of burning uses three boards strapped together to create a flue that is lit on fire from the inside. However, most Westerners use a type of torch that is typically used to melt ice and snow attached to a propane tank. In the past I have created a couple of large tables where I used fire to apply a finish, and I enjoyed the process and results both times. However, with each project, I had a separate learning curve and used different woods. Here I will describe the process of making these tables and explain the differences in the results I achieved from ‘Yakisugi to Gendai’.
Outdoor gendai table
My Gendai table was made over five years ago for use in my own backyard. In the winter here, temperatures are around -34°C (-30F) with plenty of snow, so the table needed to withstand these harsh conditions.
For the table top, I used a large Western red cedar slab that I had been saving and two white oak casks for the legs. Torching the white oak took longer than the cedar due to the density of the wood. After torching, I cut off the top of each cask to make them the correct height for the legs. Since the general shape and appearance of the slab matched what I wanted for the table, I hand-planed and sanded the surface in place before torching.
When I began to torch the top I realised I needed to move the slab further from the house as the paint on the building was starting to curl. I finished a nice alligator scale appearance on the entire top before finishing up the height adjustments; I then began to wire-brush off the surface. After removing any loose material, I used a Danish oil to penetrate the wood and rehydrate it before I applied some polyurethane to reduce sun and weather damage even further.
The final result made the family happy and has lasted well over time as there have been no noticeable changes so far. The grain has some interesting texture to it because of the double- brushing technique, which isn’t enough to unsettle a drink, but does give some grip to plates and glasses.
Yakisugi boardroom table
The second project where I used the burning technique was when I was hired to build a boardroom table. This was a commemorative piece for a modern architectural design firm and was going to be part of a US$250 million project; it was to act as a reminder of the firm’s early projects. The client had a few loose requirements: the table had to look amazing, be 1.2m wide by 2.4m long and contain a 0.9m cutout in the centre for its original design-build book to be enclosed in, so that when a glass top was placed over it the book would be visible, but not touchable.
The design firm uses a lot of glass, steel and stone in its work and in its own office, so the wood was to soften the look but also blend in with its surroundings. The boardroom walls were going to be charcoal, so I chose steel wishbone legs painted matte black, and the yakisugi finish to bring the outside to the inside. The glass would protect and prevent any soot left in place from getting on to business suits and fingers, and the edges and bottoms had a Gendai feel and finish to them.
The firm had used a lot of old-growth Douglas fir in its early projects, and I was able to use some urban recycled Douglas fir, which initially started out much larger than I could use for the table at 1.8m wide and 3m long. The log was rotted in the interior, which broke each slab in half, so I elected to cut the boards down with a beam saw into 405mm widths or less for easier jointing and planing.
Torching and then fitting each piece in place was more difficult than I had anticipated. The firing process caused enough warpage of each piece that the joints were no longer closed tightly, even though the depth of the burn was minimal, which meant they were no longer flat enough to have glass placed over them. Thankfully, I had kept everything larger than I needed, and I was able to rejoint, replane and finally glue the pieces together.
Refiring caused the aliphatic (yellow) glue I had used to loosen, but I noticed it quickly. I reglued using clear construction adhesive and again noted some loosening during firing, but less than with aliphatic glue. Once I had the pieces fired and stable, I adjusted any warped areas that would not fit perfectly under the glass and refired in those areas using a small hand-held propane torch, while avoiding any areas joined with glue.
Because the glass was made with very tight tolerances, I used a sheet of 3⁄4 plywood cut to size perfectly and a pattern-bearing bit to make my final sizing adjustments with hand-refiring again. I was happy with the final surface but did notice some pitch that came to the surface and changed areas to a lighter colour. These areas also remained smoother. I cut the centre out and placed some L-shaped blocks under 14 the table that were adjustable to raise and lower the book on each side for a tight, flush fit against the glass.
A final coat of furniture polish was applied to keep soot from coming off on hands, clothes and the building during installation, and it was ready to be delivered. The delivery was made while the freight elevator was still available full size, and the table was carried in with the legs attached – this process was made much easier with the extra help of four sets of hands!
The project was finished with the installation of the book, some on-site levelling and the glass being applied carefully. With the book safely displayed under a half-inch of glass, the chairs were brought in for the first meeting.