Wood burning - from protection to staining

At first glance, burning wood can be a topic that, if not frightening, certainly saddening. With this in mind I even had an article at one point about protecting wood against fire by treatment with flame retardants. Yet, how did we get from fire protection to protection and staining with it? Why do I claim that it does wood good if you burn it? It is what I intend to tell you next.

Protecting wood with fire was discovered by the Japanese in the 1700s (according to some documents even earlier). The method is called Shou Sugi Ban (in translation, burnt cedar plank) or Yakisugi. They saw that burning the surface of the cedar plank (sugi) until charred made the wood highly resistant to weathering, rot and insect attack, making it very suitable for outdoor use. The method was used extensively until 100 years ago when the advent of modern building materials (cement and later plastics), combined with a shortage of indigenous wood at the time, almost led to its demise.

In the 2000s the technique was rediscovered and quickly came to the attention of designers and architects in Europe and North America. The enthusiasm was so great that burnt wood went beyond fencing and cladding houses and came to be used extensively in interiors, for flooring, wall decoration and furniture. Producers have emerged who industrially produce burnt wood and then process it to enhance its beauty.

Basically, the method consists of burning the wood using various processes (gas burner, direct flame burning, practically setting the wood on fire, etc.), extinguishing the fire and cooling the surface using water and cleaning the burnt surface. This cycle can be repeated several times until the desired result is achieved. Surface cleaning is done with wire brushes and can be done only superficially or in depth.

Wood burned in this way can be used to build houses, fences or for other outdoor uses. The charcoal coating has good protection against UV radiation, and it is considered that such wood can last 80 to 100 years without any maintenance. The wood can be used as it is or, after brushing, treated with oil.

Starting from the basic steps of the method, all kinds of techniques have been developed to produce surfaces with different textures and colours. Burning can be done with varying degrees of depth. Water cooling can also be done in different ways: by pouring a large amount of water directly onto the plank or by slowly dripping water. This gives different structures to the burnt wood, controlling the break-up of the 'charcoal' layer on top.

Cleaning wood can also lead to various effects. It can be cleaned only to remove the soot layer on top and get to the stable burnt part, or that part can be removed too, more or less, depending on the desired design. It can be obtained like this structured wood.

How does the structuring work? Early wood, being softer and looser, burns faster than later wood. When the burn is removed by brushing with a wire brush, more material will be removed in the early wood area and so the late wood will stand out.

The way the burnt wood is cleaned can also be used to stain the wood. By brushing the wood, the part that is cleaned first is the late wood, where the natural colour of the wood appears, and the rest remains the black colour of the charcoal. The wood will then have a patinated appearance.

But the most spectacular is when you combine burning with bathing. The wood is brushed to partially remove the burnt part and a bath is applied to the surface. The burnt area does not absorb colour, remaining black, unlike the area where the wood has been reached and the berry is absorbed normally, staining the wood. The combination of applied colour and charcoal black is truly spectacular.

While the method was initially applied to Japanese cedar, it was gradually extended to other species. But it looks best on softwood (fir, pine, spruce, douglas fir) and especially when it is cut so that it has a flare.

Staining by burning can also be done without the wood being charred. By surface burning, early wood will be the first to change colour, bringing out the natural pattern of the wood. Burning is done with a simple gas torch, and complicated, high-powered and more dangerous equipment is not needed.

Once so stained, the wood can be protected by applying varnishes or, much better, by applying oils.

The method has now gone far beyond its use as outdoor protection and has entered the field of interior design, but also furniture and decorative objects. The special effects that can be achieved by carefully controlling burning, brushing or staining have allowed it to be used to decorate more special objects such as jewellery boxes or even electric guitars.

This is a colouring method that you can also use in diy projects. It's good to remember though that wood burns easily and to be very careful when doing this. And if you don't have the conditions or the skills, it's best to leave the staining to the professionals.

Another interesting method with spectacular but also extremely dangerous results is electric wood burning. I don't recommend it, but I think any information is welcome even if we don't put it into practice.