Charred Wood for a Fiery Finish
The look of charred wood is a hot trend for home décor. The practice of charring wood, called “Shou Sugi Ban,” originated in Japan centuries ago as a method to preserve cedar siding. These days, this wood-burning technique is now growing in popularity in the U.S. and Canada for its decorative appeal. Demand for this distinctive look is so strong that manufacturers now offer “charred” finishes straight from the factory for house siding and wall décor panels.
The procedure involves charring the wood with the flame of a propane torch, then cooling the surface, cleaning it with a wire brush, rinsing off the residue with clean water, and applying a finish coat.
The natural durability of Shou Sugi Ban makes it appropriate for interiors or exteriors. It’s an excellent alternative to paints and stains. Depending on the heat and cleaning technique, you can achieve a broad range of textures and tones. The final product can have a rich, silvery finish, or you might prefer to show off the deep contrast between bands of wood grain, enhancing the natural beauty.
Charred wood resists fire, rot, insects, and can last for decades. This wood-finish application can be used for siding, accent walls, window shutters, wainscoting, column/beam wraps, outdoor benches, and all sorts of creative applications.
Wood Charring Basics
It should go without saying that working with fire is dangerous, and one should take all precautions to ensure a safe working environment away from combustible materials and with plenty of ventilation.
The best way to dive into wood-charring is to experiment, because the practice is as much art as science. Furthermore, different types of wood species will react differently to varying
levels of flame exposure, and ultimately the cleaning technique can impart dramatically
different effects to the charred surface.
It should go without saying that you’ll need a safe place to work with open flame, away from any notably flammable materials.
The good news is you don’t need to experiment on expensive lumber. When selecting wood for charring, look for construction-grade softwood lumber, such as pine, spruce and fir, which have a soft grain. After you burn the surface, the cleaning process will scrape out the soft springwood between the bands of woodgrain, and it’s much more difficult to remove that material when working with hardwood.
The soft whitewood species are also lighter in color, which works like a blank canvas for
the coloration to follow. For the most dramatic charring effect, choose wood pieces with the lightest color available.
Grain orientation is also worth noting. When preparing to char, check the board’s end-grain for the growth rings. You should apply the flame to the bark-side of the tree for the most interesting grain pattern.
Finally, look for lumber labeled “KD,” which stands for kiln-dried. Wood with high moisture content won’t dry out and therefore won’t work well for the charring technique.
Traditional Shou Sugi Ban, which literally translates to “burnt cedar board,” involves tying the boards together in bundles of three to form a triangular chimney, then placing them on-end over a fire, so the flames draw upward and char the inner faces of the boards. Once charred, the boards are removed and cooled with water, stopping the burning process and hardening the blackened, charred surface. The cooled, black surface becomes resistant to sun and rain, insects, rot and fire itself.
The first pass with the torch will remove moisture and prep the boards for charring. The second pass will begin to show a change in the wood’s color tone.
You’ll need to take a cue from tradition when setting up your work area, because the charring works best on vertically oriented boards as heat draws the flames upward. A welding table can be used to provide a non-flammable working surface, or you can use a wood workbench if you don’t mind the likelihood of char marks.
For smaller projects, a Berzomatic torch (propane or MAPP gas) can be used to char the wood surface. For larger projects, a weed torch that connects to a propane tank will produce a larger flame.
Support the workpiece vertically against a bench, then pass the torch flame over the wood surface along the same direction as the woodgrain. Move the flame in a consistent pattern with smooth, even strokes to avoid blotchiness as the wood darkens. Keep the flame the same distance from the wood throughout the process.
Make a first pass over the entire face of the board. It will have some charring effect, but the first pass basically removes moisture and heats the wood in preparation for the following passes, which will char the grain and springwood. The soft springwood will burn faster and deeper than the hard grain. Note that if you plan to brush out the softwood for a high-contrast grain effect, then you don’t need to burn the wood to the point that it looks like firewood. If you plan to remove the springwood, you only need to blacken the entire board surface.
Move the torch along the same direction as the woodgrain. Charring works best with the boards in a vertical position, which may require a ladder to char long boards.
Reposition the boards as necessary to apply heat to all sides and edges.
The resulting finish will depend on the degree to which the surface is burned, or how long the wood is exposed to the flame. For a more blackened end product, a different surface effect can be achieved by charring the wood until it won’t take any more flame. This technique ultimately makes the board surface more fire-retardant but also distorts the surface with a distinct alligator-like texture. The surface can then be brushed to even the color and then clear-coated to finish.
For best results, char and clean the individual parts of your project prior to assembly. Shown to the left, we’ve moved from 1x6 tabletop boards to a 4x4 table leg.
Note that the heat from the flame can distort the shape of the boards and cause bowing, particularly with thinner material, but application of clamps and/or weights and fasteners can usually muscle the boards back into shape when cooling them.
Cleaning the Boards
Once the wood has been charred, a variety of brushes can be used on the surface for
different looks and textures. A nylon utility brush works well to remove loose char and achieve a fairly uniform sheen. The stiffer the bristles, the more aggressive the scraping action, which removes more char, revealing the lighter springwood beneath but leaving
the dark rings of the harder grain for a higher contrast. Use wire brushes with bristles of
different stiffness (stainless steel, brass, etc.) to vary the tooling effect. Drill-mounted brush attachments can also speed up the process.
Use water to rinse off the loose char dust then allow the wood dry completely.
Charring is only half the process. The wood’s finished appearance will largely be determined by the brushing and cleaning process.
For a charcoal-textured or “dragon scale” appearance, apply enough heat to fully blacken the wood surface then use a soft-bristle brush to brush away the dust and loose char.
For a smoother, more uniformly silver appearance, blacken the surface but stop charring when the texture begins to distort. Brush and clean with the soft bristles of a nylon utility brush or even a paint brush.
The stiffer the bristles, the more aggressive the cleaning action. A wire brush can remove bands of soft springwood while leaving rings of darkened hardwood for a high-contrast grain effect.
Power tools can speed the brushing process, such as these Nyalox flap wheel accessories which attach to a drill.
For an artistic effect, combine the high-contrast grain patterns with colorful wood dyes and stains.
After you’ve brushed and cleaned and dried your charred wood, it can then be clear-coated to preserve its natural color or be enhanced with the use of a stain or dye. Brush the colorants onto the wood surface, then wipe off the excess to leave the desired tint.
For top coats, try a water-based product such as Polycrylic from MinWax and the thicker Enduro-Var urethane from General Finishes (excellent for coating a fully charred wood
Charred woodgrain is a great look for wood lovers, a popular décor for homeowners, a new finish that the pros can offer, and a fun hobby for DIY’ers to explore. Give it try, but please be careful.
Preserve the charred wood with your finish of choice.
Here’s the finished project—a 6’ patio table made of charred pine.
SIDE NOTE 1
Charred Cedar Shutters
Sho Sugi Ban works for interiors and exteriors. For a golden brown, oven-baked color tone, char the boards until barely blackened then brush with a stiff-bristle nylon brush.
SIDE NOTE 2
The look of charred wood is so “hot” that manufacturers such as Thermory USA offer cladding options prefinished with a Shou Sugi Ban look, which can be used for exterior siding or interior accents.
Ignite cladding from Thermory USA provides the look of Shou Sugi Ban with durability all the way to the core. And unlike charred wood, Ignite has no messy residue, offering the realistic look of charred wood, without the flames. The cladding is created from thermally-modified wood using a process of heat and steam that enhances the wood’s stability and lessens its weight. Ignite achieves its signature dragon-scale pattern by embossing, brushing and tinting thermally modified Scots pine. Unlike modern Shou Sugi Ban, which is usually created by hand with a torch, Ignite is created with a deceptively flame-free process. It is also available with only the brushed texture. The thermal modification gives the wood consistent rot resistance throughout the board, a high level of dimensional stability, and a consistent appearance from batch to batch. Learn more at www.thermoryusa.com.
SIDE NOTE 3
Video: Charring Wood for Home Projects