If you love wood, you surely want to keep all your pieces in the best possible condition.
To do so, you need to protect the wood from moisture and pests. So stick around and we’ll show you the various treatment options available for you.
This way, your old and new pieces will be out of danger and besides, will look as if they just came out of the carpentry workshop.
How to treat wood?
To begin with, we must be clear that treatments applied to wood are intended to protect it from abiotic agents such as humidity, or biotic agents (pests) such as termites or woodworm.
Likewise, not all woods require the same treatment. In fact, a classification exists that groups the woods according to their use, and from it, we can know which is the best treatment for each wood.
Classification of woods according to their use
Next, we are going to describe how wood is classified according to its use in accordance with the European standard UNE-EN335, which establishes the concept of the natural durability of wood.
This standard establishes 5 classes of uses for wood, but in fact, 2 large groups are explained:
- Interior woods.
- Exterior woods.
Then, from these 2 groups, we can know what kind of agents are the most likely to attack the wood.
Group 1 interior kinds of wood (classes 1 and 2)
Class 1
Class 1 wood is wood used in covered environments, i.e. pieces of wood that are not exposed to the weather.
This class includes pieces such as:
- Interior doors.
- Skirting boards.
- Window frames.
- All types of home furniture.
In general, if these pieces are made of solid and durable woods such as American or European Cherry wood, most probably no special treatment will be needed to preserve them in an optimal state.
However, if the pieces are made with less resistant woods such as Pine, Fir, Ash, Maple or Eucalyptus among others, treatments will be necessary.
Main pests that threaten this wood
– Beetle larvae (woodworm).
– Termites.
Treatments for class 1 kinds of wood
Brushing
This treatment consists of applying substances that protect the wood using a brush or roller, i.e. the product is spread over the entire wood surface.
This type of treatment is used to coat the wood superficially.
Spraying
A cloud of waterproofing and insect-repellent substances is applied directly on the surface of the wood using compressed air.
Like brushing, this method provides surface protection only.
Heat-treated wood
On the other hand, if the wood is not impregnable, i.e. it doesn’t allow the absorption of protective materials, we may have to resort to options such as thermo-treated wood.
This wood undergoes a heat treatment that increases the wood’s resistance by exposing it to heat and then applying protective oils.
This method can increase the lifespan of the wood by several decades.
Class 2
These woods are similar to Class 1. However, they may be slightly more exposed to moisture.
Main pests threatening these woods
- Woodworm.
- Termites.
- Rot fungi.
We can find this type of wood in places close to a swimming pool, on the inside of roofs or in beams.
These woods don’t need treatments either if they are species of good natural durability.
On the other hand, if the natural durability of the wood is low, you can use the same treatments used for class 1.
To give you an idea of which woods most often or always need treatment, here is a list (not all woods, just the most common ones).
- Pine.
- Spruce.
- Birch.
- Maple.
- Paulownia.
- Eucalyptus.
- Acacia.
- Beech.
- Poplar.
- Tuya (Canadian tuja).
Group 2 exterior kinds of wood (classes 3, 4 and 5)
Class 3
This class is divided into 2 smaller classes according to how much the timbers are exposed to the weather.
Class 3.1
These timbers are outdoors but don’t touch the ground, which is where moisture accumulates the most.
These woods are found in places such as gardens, roofs or exterior window frames.
Main pests that threaten these woods
- Woodworm.
- Termites.
- Rot fungi.
Treatments for class 3.1 timbers
Exactly the same as those used for class 1 and 2 kinds of wood.
Class 3. 2
The timbers of this class are also above ground. However, they are at greater risk from contact with water.
Examples of this class of wood are the beams that support the weight of a bridge.
Main pests that threaten these types of wood
- Woodworm.
- Termites.
- Rot fungi.
Treatments for class 3.2 timbers
Autoclave
If the woods are not durable, treatment alternatives such as autoclaving are available. This is a metallic container in which compounds such as copper salts are applied under pressure through the wood to provide deeper protection, as opposed to brushing.
Class 4
This type of wood is in permanent contact with the ground, but can also be in continuous contact with fresh water.
This wood is found in places such as bridges crossing a river or some other body of water.
Main pests threatening these woods
- Bacteria such as the bacillus amylobacter or bacillus methanogenesis feed on cellulose, the substance that gives the wood its structural support.
- Woodworm.
- Termites.
- Rot fungi.
Treatments for class 4 wood
Autoclave
When wood is not durable, treatments such as autoclaving should be used as high temperatures can create a new layer of burnt wood that resists attack by pests and also waterproofs the wood.
Acetylated wood
Acetic anhydride is added to the wood by chemical processes.
This makes the wood more resistant to pests and humidity as the acetic anhydride permeates both the surface and the interior of the wood.
Therefore, woodworm, termites, and fungi cannot decompose this chemical substance and, therefore, wood degradation is reduced.
Class 5
Class 5 kinds of wood are exposed to salt water, so not just any wood can be used.
The applications of these woods are:
- Dock construction.
- Construction of bays.
- Construction of boats.
Main pests that threaten these timbers
Marine borers are mollusks or crustaceans that feed on wood cellulose.
Like termites or woodworm, the damage caused by these organisms is not visible from the outside.
However, they can affect the surface of the wood when they emerge.
Treatments for class 5 kinds of wood
These woods don’t usually require major treatments as they are often the most durable woods.
However, treatments such as acetylated wood or autoclaving may be useful if, for some reason, you have chosen wood of medium or low durability.
Other wood treatments
There are other (often more common) treatments that can reinforce the natural durability of wood.
Lasur
This is a treatment almost exclusive for exterior woods and consists of applying a very impregnable substance, that is to say, easily absorbed by the wood.
Thus, the lasur expands and makes the wood more robust. This means that the wood is more resistant to weathering, making it better able to withstand direct and prolonged exposure to solar radiation.
Likewise, lasur has an insecticide and fungicide action as it prevents insects and fungi from digesting the wood.
Teak Oil
Teak is probably the wood with the greatest natural durability in the world and this is mainly due to the natural oil it exudes:
- It protects it against humidity (it repels it).
- It moisturizes it in dry seasons by creating a layer against solar radiation.
- It makes it difficult for pests to adhere to its surface and, if they are able to penetrate the wood, the oil can be toxic to insects.
It is therefore not surprising that this oil is used on other woods (which lack the oil naturally) to increase their durability.
Also, keep in mind that this oil is colorless and therefore does not alter the aesthetics of the wood.
Varnishes
Resins are natural substances produced by several species of trees, especially conifers such as pine.
They allow the tree to moisturize its wood and, in addition, help to heal wounds caused by blows and/or pests.
Varnishes are a mixture of resins and natural oils.
These varnishes are used as paint and are applied on the surface of the wood to be treated to avoid the deterioration that weathering causes to the wood.
Varnishes come in different colors and textures to suit any wood.