How to keep wood from cracking when burning with a torch?

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Written by Jared Watson

Jarred Watson is a pyrographer with 10+ years experience and has worked with brands like BOSCH & FORD. He is always looking to learn and share his passion of wood burning with others.

Wood burning or pyrography is a beautiful burning of designs and patterns on a wooden surface, mainly done using a heated tool. Applying a finish on the wooden surface is an essential step, as a wood-burning finish helps in preserving the art piece. Often a hand torch is used for applying a finish to the wooden surface.

It often happens that, while burning the wood with a torch, the surface of the wood cracks or splits. One can wonder why it happens at all. Wood contains moisture and minerals and is wet if the wood is freshly cut.

Even if it is seasoned, some amount of moisture remains in the wood. When heat is applied to the surface of the wood, it gets hot and makes whistling sounds as if small fissures are releasing pressure. This is the moisture in the wood that gets converted into steam and creates pressure on the porous grain of the wood. Wood swells with moisture and shrinks as it dries when heat is applied.

When heat is applied to the wood, it burns on one side of the log, usually on the outer side. This differential heating causes one side of the wood to shrink rapidly while the other portion swells up. The stress created against the grain of the wood due to the varied rapid drying and shrinkage causes the wood to crack and split. The wood can also crack if the wood is way too dry. Other factors like using screws or nails on the wood split the fibres of the wood, creating an imperfect joint and splitting it.

Ways to prevent the wood from cracking

Cracking wood is the worst nightmare for any wood-burning artist. A newly cut green wood with high moisture content is highly prone to splitting and cracking when heat is used. If the wood is too dry, it may split and crack even then.

Wood absorbs moisture through the pores, which are made of thin fibres. The moisture particles easily penetrate the wood when humidity increases, causing it to expand and pulling its joints apart. Similarly, the shrinking movement has enough power to pull the joints apart when the moisture level is low.

To prevent the wood from splitting and cracking, one has first to get familiar with the movements of the wood. Since the movements made by the wood cannot be controlled, you can follow certain methods to join them that would make them resistant to humidity changes and stop them from cracking. The following are a few of the methods that can be used to prevent the wood from cracking.

Apply sealant or stabilizer

One of the first ways to prevent the wood from splitting or cracking is by applying a sealant or stabilizer. This is one of the easiest ways to use as it is effortless to follow without any issues. A sealant or stabilizer prevents the wood from drying, preventing shrinkage. It locks the moisture inside and prevents outside air from contacting the wood.

To apply the sealant or stabilizer, you would need a sealant or stabilizer, a paintbrush and rubber gloves. If you have a Greenwood, an anchor seal is the best sealant you can use. For other furniture and wood works, you can use polyurethane, a lacquer-type sealant with good waterproofing capability. Since the sealant and stabilizer are made of chemicals, it is essential to wear protective gloves to protect your skin from such chemicals.

Before applying any kind of sealant or stabilizer, it is essential to ensure that the wood’s surface is clean. Applying the sealant over dirt and debris will give a blotchy appearance. Once you clean the wood, sand it with 220 grit sandpaper. Sanding the wood makes the surface smooth and helps the sealant to set correctly.

Clean the surface with a wet cloth after you are done with sanding. Let the wooden item dry completely before you apply the sealant. Apply the sealant with the help of a paintbrush in thin layers and evenly throughout the wood surface. If it is not spread evenly, the spot where the sealant has not been applied will come in contact with the air and make the wood split or crack.

Apply salt paste

In case the moisture inside the wood is causing the split, slat paste can be used to dry the wood. Salt paste absorbs the moisture inside the wood and assists in drying it. The salt paste is easy to make and does not have any chemicals in it; therefore safe to use and one of the easiest methods to prevent the wood from cracking. 

To make a salt paste, you would need Salt, Cornstarch, and Eggs. To make a salt paste, you must prepare a salt solution. You would need to take a bucket and fill it with fresh water for the salt solution. To the bucket of water, you need to add table salt and stir it until it has dissolved completely. 

Make sure not to oversaturate the water with salt. Once the salt has dissolved, keep the solution to rest for four hours. After four hours, add cornstarch to the solution and mix it well. Be careful of the amount of cornstarch you add, as an excess can make the mixture hard. 

After you have added the cornstarch:

  1. Add three eggs to it and mix it until the eggs disappear into the solution.
  2. Once the eggs are mixed well, apply the mixture on the wood evenly with the help of a paintbrush.
  3. Use it all over the wood in a uniform layer without missing a spot. The salt paste will not come off easily once it is applied.
  4. Let the salt paste dry once it is applied by leaving it in a warm area. The salt paste will make the wood dry by absorbing the moisture from the wood and preventing it from cracking or splitting.

The time to dry will depend on the amount of salt paste you have applied. 

Use varnish

Varnish is another product that can be used to avoid the splitting and cracking of wood. Varnish has a sealing property which seals the moisture inside the wood and prevents it from evaporating out from the wood.

To varnish your wood item, you need a fresh can of varnish, warm water, wood glue, a paintbrush, cloth or rag, and sandpaper. Before you apply the varnish, it is crucial to prepare the wood by sanding it with the help of sandpaper.

Use 220 grit sandpaper for this purpose. Sanding the wood will open the wooden grains and help them to absorb the varnish better. Sand all over the wood and do not miss any area. After sanding the wood, clean it with a wet cloth or rag to ensure there is no dust, debris, or sawdust.

Next, you must prepare the varnish by pouring equal parts of spar varnish and aluminium paint into a big bucket. Stir the mixture well. Once the varnish is prepared, you would need to prepare the sealer by adding wood glue in warm water. Stir this mixture well to ensure the wood glue has completely dissolved in the warm water. The water should be warm enough so that the wood glue can dissolve.

For the application part, you need first to apply the varnish. Apply it all over the surface of the wood evenly and in thin coats so that it can dry quickly. Apply two to three coats of varnish to get the required protection. Once the varnish has been applied and dried, you can seal it using the sealer. The sealer acts as an extra layer of protection that prevents moisture evaporation and avoids wood shrinkage.

Apply paintable wax

Another easy and cheap method to keep the wood from cracking and splitting is using paintable wax. It is a great product to protect greenwood from cracking and splitting. Paintable wax also prevents the moisture inside the wood from escaping, thus preventing the wood from drying up. For applying paintable, you need certain equipment like Wax candles, Paint thinner, Hammer, a Food scale, a Canning jar, and Paintbrush.

To make paintable wax, you would first need to prepare the wax. The wax can be easily prepared at home without buying it from a store. All you need is a regular wax candle and a plastic bag. Hammer the candles inside the plastic bag till there are small bits of the wax candle.

Once the candles are powdered, measure the weight with a food scale and put it in a pot or any other heating device, and heat the wax powder till it has melted completely. After the wax has melted, add paint thinner in it in the ratio of one-fourth of the weight of a plastic bag filled with wax. Shake the mixture to mix it evenly.

Apply the paintable wax all over the wooden surface uniformly with even pressure with the help of a paintbrush. Make sure to apply thin coats as it will take less time to dry. Cover the whole wood surface. You must include the edges and corners. Paintable wax will assist in protecting the greenwood from environmental elements.

Apply boiled linseed oil

Boiled linseed oil acts as a guard seal which helps to protect the wood and prevent it from splittings and cracking. It is easy to apply and also highly functional. It is highly recommended, especially for beginners, given the ease of this method.

For this method, the equipment you will need is- Linseed oil, Sandpaper, Old cloth or rag, and a paintbrush. Before you apply the linseed oil, it is essential to prepare the wood. To prepare it, sand it by using 220 grit sandpaper—Sand the whole surface, corners, and edges of the wood.

Make sure to sand the wood in the direction of the wood fibres, as it will help the fibres to open up, resulting in better linseed oil absorption. Sanding also helps to preserve the wood. Clean the wood with the help of a wet cloth once you are done with sanding to ensure there is no residual sawdust, dirt or debris. It is essential to clean the wood surface, as boiled linseed oil will not get absorbed if applied right after sanding.

Once you clean the wood’s surface, you can apply the boiled linseed oil. Apply it throughout the wood without missing a spot. Put thin coats of linseed oil to dry easily. The first coat will get absorbed into the wood with little left on the top.

Therefore apply two to three layers of linseed oil to seal the wood completely. Apply the following layer once the previous one has dried completely. For drying, keep the wood item in a warm area where it won’t be exposed to sunlight, as sunlight can damage the linseed oil.


When working on a wooden item, you want it to have a long service life. For that, you will certainly use various types of chemical finishes on untreated wood, which will help preserve the wooden item for a prolonged time. Though chemical sealants are very popular for maintaining and making the item visually appealing, another method does not involve such chemical sealants. This method is known as the art of Shou Sugi Ban, which involves burning wood.

Shou Sugi Ban, also known as Yakisugi is a traditional Japanese technique practised for centuries as a finish on wooden items method, giving a unique and rustic appearance to the wood item. The central theme of this method is to burn the wood to form a black layer of carbon on the top surface of the wooden item.

Traditionally, in Japan, it was done by creating a triangle using three wooden planks to form a fireplace and then the fire was lit at the base of the chimney. The fire rises and burns the wood evenly, and it is brushed and wiped accordingly. This traditional way of doing this method is not easy and comfortable for a regular individual. As a result of which, today, you can find an array of alternatives to this technique.


When practising Shou Sugi Ban to apply a finish on your wooden surface, it is essential to maintain certain safety precautions to ensure your safety and prevent accidents.

Safety Gear

It is vital to wear proper safety gear as you will be working with an open fire when doing the burnt wood technique. The carbon formation happens at a temperature of 500°C. Therefore, you should wear thick heat-resistant hand gloves to protect your hands from getting burnt. Also, smoke will be produced as you will be burning the wood.

If you inhale the smoke, it can damage your respiratory system. To avoid any such situations, wear a respiratory mask which has organic filters in it. The mask will also prevent any char or ash from entering your lungs. You can also keep a stand fan nearby which will help you to disperse the smoke. Also, wear a safety glass as the sap from wood may bubble and pop when exposed to an open flame.

Should be Practiced in an Outdoor Area

Since the art of Shou Sugi Ban involves using open fire, it is recommended to do it in an open area. Using a blow torch, which produces a high amount of heat. Working with such equipment in an enclosed indoor area can lead to many hazards. The area where you will be working should be well-ventilated and spacious.

Check or Flammable Items

Before you start with your work, ensure that your workstation does not have any items that can catch fire or are flammable. Items like paper, oil, and plastic can be highly flammable and, if in close vicinity of such high temperatures, can cause accidents. Keeping a fire extinguisher or a spray bottle of water is recommended in case of any flare-up.

Every tool in the wood burner kit comes with a wattage rate, which is the intensity of power produced by the pen. The good quality pyrography tools come with a 60 Watt power rating. However, if you are a beginner in pyrography, it is better to start with a 15 to 30 Watt tool. It wouldn’t be smart to think that a high power wood burner will be the best one to have; the tool might leave dark burn marks on the wood if you hold the pen for quite a long time on the same spot. 


Thus, if you face the problem of cracked wood every time you work on a wooden item, you can follow any of the given methods to prevent it from happening. Once you understand why the cracks and splits happen in the first place, it will not be difficult to prevent them. The above-mentioned methods are effortless and economical and do not involve complicated ingredients.

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