Introduction: How to Shou Sugi Ban Wood Burning on Deck Boards - Beginner's Guide
Hey everyone, welcome to Homes for Beginner where I show you how to do repairs around the house yourself. In this video, I will be showing you how to do shou-sugi-ban on deck boards. I will be covering the history along with the benefits of this type of wood treatment further on in the video. First off I am doing this on untreated wood which is important. Any wood treatments such as pressure-treated which has a chemical applied will cause fumes which can be hazardous to your health.
- boiled linseed oil
- metal bowl or pot brush
- brass wire brush
- small propane soldering torch with bottle
- large propane torch and tank
- wrenches for propane line fittings
- untreated deck board
- insulated or leather glove
Step 1: Preparation
The boards have already been cut to length, I’m only doing two at a time so I don’t get mixed up. I have found marking the ends with a pencil can be done and there will be a very light outline but it can be hard to read. The deck boards are being screwed down so all the holes have been pre-drilled as well. Marking out any of this stuff after can be a bit messy dealing with the ash and the markings can be hard to see too.
Step 2: Burning Setup
Next is moving onto burning. If you are new to this, I would highly recommend testing this method out on a piece of scrap wood first. Here I am using a propane torch which is typically used for burning weeds but it has other purposes as well. The hotter the flame, the quicker the burn so set it to whatever you’re comfortable with. I have been experimenting with different days and techniques so I’ll try to cover everything I have experienced. I have found it’s easiest to start with the sides of the boards first. Don’t put the boards together, any small gaps between the boards due to bowing may not cause an even or clean burn. Place the boards in an area where you won't risk damaging the ground such as grass or surrounding objects. The boards have been placed on concrete blocks which are resistant to the heat.
Step 3: Burning the Boards & History
Any knots in the wood won’t burn like the rest of the grain. Those can be left as is or you can touch them up with a torch after. Not all grain burns the same either, some burns slower, others burn quicker and this depends on the cut of the wood. If the wood isn’t dry, you’ll see and hear the wood popping which isn’t a problem. While I am using kiln-dried wood, unfortunately, it isn’t very dry when purchased from the lumber yard so this is a fairly common occurrence. Edges will burn quicker than flat areas, the efficiency of burning can be affected by the temperature outside along with the wind. It’s best to do this on calm warm days, even with a higher flame, the wind can greatly increase the amount of time required to burn the surface. The distance you hold the torch away from the wood can also affect how quickly the wood burns, so experiment with that too. These are 2x6, 12 feet in length and it takes about 10min per board to burn. The board must be burned all the way around to provide a proper barrier. Only burning it on the top still allows the wood to be affected by the elements from the sides and underside. The boards will be warm, so handle with care.
As a little history behind the shou-sugi-ban finish, I have been cross-referencing multiple sources for information. This method dates back at least a couple centuries and was a traditional Japanese method to treat wood, specifically Cedar. For this I am using Spruce, Cedar is the best type of wood used due to its properties, however, it can be used on other woods but results will vary. This type of treatment is intended to have a much longer life than compared to other wood treatments, this can be done in a variety of burns achieving different colors or finishes, is water-resistant, fire-resistant, and insect resistant.
Step 4: Knots and Cut Ends
When done with the main burning, the cut ends, knots, or any low spots can be touched up with a small handheld propane torch. The knots can be left as is, but I prefer having a consistent look. The large torch doesn’t burn the cut ends as well so a more concentrated flame is needed for that. If you have found spots were sap has seeped out, the sap does make some areas resistant to the flame and this can be touched up with the handheld torch too.
Step 5: Charcoal Finish
The wood can be left with the charcoal finish on the outside or this can be cleaned up. I am currently experimenting with leaving the charcoal surface on and it’s holding up extremely well with very light wear. Regardless of either finish, the wood still needs to be oiled.
To clean off the charcoal, I am using a brass wire brush. The brass is soft so it won’t be excessively course on the wood as compared to a steel wire brush, however it still cleans off the charcoal efficiently. Do with the grain of the wood, not against as it can make marks in the finish.
The more you drag the wire brush on the surface, the more it’ll clean off the burnt finish and the lighter the wood will be. Clean off the loose charcoal with a broom, compressed air or a vacuum with a blowing feature that can also be used.
Step 6: Preparing the Linseed Oil
Moving onto oil, for this, I am using boiled linseed oil which has a different chemical composition as opposed to regular linseed oil to improve dry time. I’m also heating the linseed oil with a torch to make it a thin viscosity, allowing it to soak into the wood quicker.
After it has been heated up, the torch is turned off and now is adding an equal amount of turpentine, so a 50/50 mixture of boiled linseed oil and turpentine. The turpentine further improves dry time and it’s ability to soak into the oil. The linseed oil will provide a light amber color, but most importantly seals the wood. Adding the turpentine after it's been heated up will reduce the stronger smell and reduce evaporation when it's being heated up.
Step 7: Applying the Linseed Oil
Wear a glove when dealing with the hot metal bowl, using a brush to apply it to the top and sides. As a cautionary tip, linseed oil is known to spontaneously combust, so any items soaked in it such as rags should be washed with water and left outside to dry before disposing of.
As you can see I am applying a fair amount to the wood and it does soak in within a couple minutes. The torch does dry out the wood which is great for applying the oil. This is all being done in one day so the moisture in the air doesn’t have a chance to soak into then. Make sure you work in a well-ventilated environment as the fumes can be strong.
Step 8: Waiting for the Other Boards to Dry
While that is drying, I can move onto the other boards. For the boards to be installed, I waited for about an hour. The oil will still be a bit damp, but it’s enough to handle the boards.
Step 9: Installation Tips and Tricks
And finally is installing the deck boards. While the frame of the deck isn’t done, it can be as well. The frame isn’t exposed to as much weather as the deck boards, but if you do have the chance to apply the same finish to your deck frame, I would certainly recommend it.
I am using 1/4” spacers for the deck boards to maintain a clean and symmetrical look. It’s screwed slowly from one end to the other, making adjustments as needed, either pulling or pushing over the boards. Reference measurements are made with the frame and existing boards, ensuring everything falls into place.
Some of these boards are crooked, so I have used different methods to pull everything together. Prying them over by hand on the milder areas or using a jack against the frame in severe situations. The older lighter boards were installed about 2 weeks ago so you can get an idea of how the finish lightens up when being exposed to the sun.
And F clamp can even be used to pull the boards down as they can lift when pushing them over. While the screws do pull down the boards when pre-drilled, it doesn’t always work fully in extreme differences. Make sure you do use quality deck screws, this deck did have then deck boards which cupped due to the weather and ended up breaking many screws in the first year which resulted in switching over to another brand.
Step 10: Final Coat & Finish
After a month just before the winter, here you can see all the boards are now the same tone and color. The boards are currently dry and before the weather gets cold and the deck is exposed to snow, a second coat of the 50/50 mixture with the turpentine and linseed oil is applied. No sanding is needed, just make sure the deck is free of any debris, so sweep it off with a broom.
The oil should be applied once a year as basic maintenance, it won’t need to be stripped or sanded. The wood will eventually become saturated with the oil, protecting it from the elements. The smell can be quite strong at first and will usually disappear in about a week. You’ll notice the finish does repel the water extremely well, maintenance is much less than compared to a traditional stain, it won’t peel, and the cost is about the same depending on the quality of stain.
And here you can see the final finish, this is a month after that second coat of linseed oil.
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