Fire retardants: varieties and features of fire protection for wood

Name fire retardant comes from Greek words anti, which means “opposition” and rur, that is, “fire”. Fire retardants are components that are added to various organic materials to provide protection against fire..

Fire retardants usually contain three groups of substances:

1. Directly flame retardants such as ammonium and boron phosphates, ammonium chloride and so on.
2. Synergists, that is, substances that enhance the effect of retardants.
3. Stabilizers. They are needed to limit the consumption of the retarder..

According to the principle of action, fire retardants can be divided into two main groups:

1. The first formulations contain low-melting salts, which increase the ignition and combustion temperatures. The released heat will be spent on melting the protective substance itself, not wood. That is, a tree can catch fire, but much later than without protection, at a higher temperature. In this case, phosphates, borates and silicates are used as basic substances, that is, salts of boric, orthophosphoric and silicic acids..
2. The second group of fire retardants, when heated, emits non-combustible gases that change the composition of the air, reducing the oxygen content. And as you know, it is oxygen that is needed for a flame to propagate; without it, the ignition source can gradually extinguish by itself. In this case, fire retardants contain sulphate gas – ammonia, ammonium sulfate.

Often, both of these methods work in combination, as part of one fire retardant, such protective mixtures are considered the most reliable.

In addition, the flame retardant composition forms a kind of crust around the wood, swelling when heated. This also slows down the combustion process, prevents the spread of fire..

Fire retardants on sale can be found in the form of varnishes, paints, mastics, pastes, impregnations and combined compositions. The easiest way, of course, is to protect the tree by applying non-combustible varnish or paint, this can be done after the completion of the construction of the bathhouse, house, facade decoration. However, experts call this option not the most reliable. Mastics and pastes are more reliable, but they are not very aesthetic and are most often used in the attic if it does not carry any functional load other than technical.

It is better to impregnate the wood with a fire retardant, not forgetting about such important structures as roof rafters. There are not enough rollers and brushes for impregnation, processing under pressure or by immersing wooden parts is required. Manufacturers often offer wood already impregnated with fire retardants.

We state: in domestic conditions, most often a fire retardant is applied in the form of a transparent varnish or non-combustible paint of various shades with a brush, roller or spray gun. But this is not a very reliable way, because many wooden knots will remain unprotected. Although this option of fire protection is generally better than none at all, the positive effect will still be.

At the factory, wood is impregnated with a fire retardant in a diffuse way, under pressure, by soaking in special baths, in an autoclave. You can also soak wood in a fire retardant bath on a construction site, but it will take time. It is most reliable to use an impregnation cylinder in industrial conditions, an autoclave, where a fire retardant under pressure, in a vacuum penetrates deeply into the wood and fills all the pores. Such lumber will be considered as fire retardant..

As for the fire protection of synthetic polymers, fire retardants are usually introduced into them at the stage of production, as well as into the finished product and during subsequent processing..

When choosing a fire retardant for your wooden structure, you should definitely pay attention to such important points:

1. Availability of a certificate of conformity, conclusion of the sanitary and epidemiological station. The certificate must contain complete information about the composition and properties of the substance..
2. Fire protection efficiency group – first or second. The first is more reliable, only 9% loss of material mass is allowed during the fire test. For the second group, this figure is 25%.
3. Wood processing method and composition consumption.
4. Service life of the protective coating. Remember that after a while the layer of non-combustible paint, for example, will have to be renewed.
5. Does the composition tint the wood (important in the case of using transparent varnishes and impregnation).

Manufacturers often offer two-in-one formulations – a fire retardant and an antiseptic. This option is called fire-biological protection. However, according to user reviews, such compositions are often less reliable, poorly protecting against biological influences, in particular, fungi and mold, or differing in low fire retardant efficiency..

At the same time, other users are sure that fire retardants are more convenient to use and are a universal way to protect wood from various influences at the same time. So the choice is yours, we advise only to pay attention to the manufacturer’s reputation and the declared properties of the fire retardant.