How to Seal Charred Wood (The Shou Sugi Ban Finish)

Shou Sugi Ban (also referred to as Yakisugi) is an ancient Japanese technique of wood preservation known to bring out the beauty of wood pieces in addition to providing the piece with natural resistance to fire, bugs, water, and rot.

This wood finishing method involves charring the wood surface with a torch and then sealing it with oils such as tung oil.

While Pure Tung Oil is the most recommended method to seal beautifully charred wood projects, other finishing oils, such as hemp oil, linseed oil, and polyurethane can also get the job done.

But before you select the best oil finish for the Shou Sugi Ban project, consider where it’s located. For instance, if it’s located indoors, tung oil is commonly chosen. But for outdoor Shou Sugi Ban wood, polyurethane is a preferred sealer due to its superior resiliency.

Sealing the Charred Wood with Tung Oil Sealer

The Shou Sugi Ban finish is visually stunning and an excellent way to preserve wood indoors. Owing to the water and fire-resistant qualities, it’s also a popular method to protect exterior wood siding, outdoor wood furniture, or other décor items from the elements.

Although the charred Yakisugi woodworking pieces are resistant to elements, using pure tung oil on your outdoor project will help further increase the resiliency and durability of timber and its lifespan. This is because tung oil penetrates deep into the wood grain and provides a protective barrier against moisture, UV rays, mold, and mildew.

1. To apply the tung oil to the charred wood, simply pour some of it onto a lint-free cloth.
2. Then rub it into the wood grain in a circular motion. Remember to work in small sections and go with the grain when applying the oil.
3. After you’re done with one section of the charred wood, move on to the next and continue until the entire surface is covered.
4. Let the tung oil sit on your Yakisugi woodworking project for about 15-20 minutes, and then wipe off any excess with a clean cloth.
5. If required, apply a second coat of the oil sealer to your charred wood project while focusing on areas that haven’t absorbed much of the oil.
6. Leave the surface to dry for at least 24 hours, and your Yakisugi project is ready for use and handle.

Many woodworkers prefer hitting this finished surface one more time with a blowtorch to get a better finish with oil sealer. But that’s completely optional.

Does Sealed Charred Wood Require Regular Maintenance?

Shou sugi ban practitioners traditionally used cryptomeria japonica, or Japanese red cedar, due to its porous and absorbent properties. However, this type of wood is not widely available in the United States as of now.

As a result, many U.S.-based Shou Sugi Ban artists and contractors utilize high-quality North American softwood substitutes, including Western red cedar, Southern cypress, and Basswood. Many other wood species like pine, oak, maple, and hemlock also work well for Shou sugi ban, although they may require different techniques or adjustments in the charring process.

Homeowners choosing the charred wood finish for projects such as siding, cladding, decking, or outdoor decor furniture, often believe that their timber does not need any maintenance after it’s sealed. But that’s not true.

Shou Sugi Ban or charred wood tends to require less frequent maintenance than non-charred pieces. However, to care for your charred timber cladding, recoating it with oil is essential.

The frequency of oil application varies depending on the wood species used, but generally, reapplying oil every 3-5 years helps preserve both the structural integrity and visual appeal of the timber.

What Can Be Used Instead of Tung Oil for Sealing the Charred Wood?

In my opinion, pure tung oil works best for indoor charred wood projects. But that doesn’t mean it’s mandatory; you can use other finishing oils like hemp oil if you do not have a tung oil wood finish available.

Hemp oil will provide the same barrier against moisture and other elements, but it may not penetrate as deep into the wood grain. As a result, you may need to apply more coats of hemp oil to achieve the same results as tung oil.

Remember that if you are working on an outdoor wood charring project (that would remain outdoors), it will need improved weather resistance. You should therefore choose something stronger like a polyurethane finish. As an alternative, you can grab an oil that’s a combination of tung oil and linseed oil, or get one that contains zinc as an additive.

It will cost you more, but the results are worth it – your outdoor charred wood project will become much more durable and weather-resistant.

The bottom line

Sealing Shou Sugi Ban is generally recommended to protect the charred wood from weathering, UV damage, and moisture absorption.

Various sealing options include oils, stains, or clear finishes, depending on the timber, desired aesthetic, and level of protection needed.

However, tung oil and polyurethane are the two most recommended options that help maintain its appearance and durability over time. Consider these options for your project, the next time you plan to finish charred wood surfaces.