Classification of fire retardant treatment of wooden structures. Fireproofing impregnations for wood - reliable protection against fire

Wood is the most common construction material. It allows us to design almost any design and create an atmosphere of comfort and warmth. In addition, wood is a natural material that has a positive effect on human health. However, there are times when such structures are at risk. For example, in case of fire. Therefore fire protection wooden structures is a desirable procedure.

Is it necessary to protect wood in this way?

The answer is clear - yes. Even the simplest treatment improves combustion resistance. At the same time, you not only protect your home from destruction, but also insure own life. And spending a little money on fire retardants can help you save a lot more money in case of fire.

Fire protection for wooden structures can cost differently. It all depends on the type of product chosen, its properties and manufacturer. In order to do right choice, you should first understand the classification of fire retardants and the features of their use.

Benefits of the procedure

Before you fireproof wooden structures, you need to consider its advantages:

1. Relative cost of processing. Whatever price you have to pay for the product, it will cost you less than a destroyed house.

2. Large selection of funds. Moreover, both in terms of application types and properties. That is different designs can be processed with different compositions.

3. Easy to use. Fire protection of wooden structures can be done by yourself. This will also save you a lot of money.

4. High efficiency. In the event of a fire, your structures may char, but will not catch fire.

5. Wide availability. You can purchase required composition at any hardware store.

Processing tasks and scope of application

Before it is produced fire protection, you need to find out exactly where it can be used and what it should provide. The main objectives of the procedure are:

1. from fire.
2. Stop the spread of open fire.
3. "Passive" localization of a fire at its very beginning, that is, without the use of any additional means.

Fire protection is used for almost all wooden structures:

1. Roof truss systems.
2. Floors and walls, both inside and outside.
3. Lumber that is intended for storage in warehouses.

In principle, such protection is used in both private and multi-storey construction.

Types of funds

Now let's look at the classification of the substances presented:

1. Fire retardants. These chemical compositions serve to prevent wood fire. They are phosphate and intumescent. Their peculiarity is that during heating they form a film that absorbs excess heat and does not allow oxygen access to the source of fire.

2. Coating materials. They consist of a binding component, often inorganic (alabaster, lime or clay), as well as a fire-resistant filler (mica, asbestos). In order to prevent a fire, such material should be applied in a thick layer. Naturally, this method has one drawback: the surface does not have a decorative appearance.

3. These products are applied to the wood in a fairly thin layer. This creates a 1 mm film, which, when heated to high temperature has the property of foaming and blocking the access of oxygen to the structure. Varnishes have the same characteristics, but they do not damage the wood. On the contrary, they can improve it significantly.

4. Impregnations. These products contain both organic components and flammable solvents. Therefore, maximum care should be taken when working with them. Fire retardant impregnation can stop the spread of fire for some time.

5. Combined substances. They can effectively protect the tree not only from fire, but also from pests (bugs, rodents and others).

This classification is the main one and makes it possible to decide on the product that will suit you best.

How to select a substance?

Before fire protection of wooden roof structures or other parts of the structure is carried out, it is necessary to purchase a suitable composition. So, when choosing, pay attention to the following criteria:

• Ability not to influence appearance processed structure. It all depends on your needs. For example, the fire protection of wooden roof structures can be of any kind, because it is not visible in the rooms where you are constantly located and does not spoil their appearance.
• The product must be approved for indoor use. That is, it should not contain any toxic elements that can cause health problems.
• Fire protection should not impair the natural properties of wood.
• Please note that the products presented may have a negative effect on metals.
• Naturally, you should also pay attention to the composition consumption per 1 sq. m. This determines how much money you spend.

Naturally, you should buy it only at certified points of sale. Each composition must have the necessary accompanying documents confirming its quality.

In principle, you can use the presented tools almost anywhere. However, there are certain caveats:

Do not apply compounds to wet or frozen wood. This will not give the desired effect.

You should not cover a surface that has already been painted with other paints and varnishes.

Fire retardant impregnation for wood cannot be used for application to other types of building materials (metal, concrete, brick, plastic).

Fire protection work can only be carried out in warm time of the year.

Features of applying the composition

First of all, remember that you should work in protective clothing so that the impregnation does not get on bare areas of the body. The fact is that it can cause burns or other damage. Before you begin, you need to collect necessary tools. It all depends on the type of fire protection. For example, you can use a regular brush or sprayer. You can also use regular immersion for a short period. However, these methods do not provide deep impregnation.

It is best to use soaking methods. This will ensure deeper penetration. Naturally, this method is more labor-intensive and time-consuming.

The product must be applied in compliance with consumption standards. Before this, it should be diluted according to the system specified in the instructions. This will ensure the effectiveness of the substance specified in the instructions. Do not work in rainy weather.

Before applying varnish or paint, the structure should be cleared of debris and dust. If there are any irregularities, they need to be processed especially carefully.

How often should the presented products be used?

Fireproofing must be done periodically. The fact is that the service life of impregnations can vary from 1 year to 30 years. The coating should be checked once every 12 months if the structure is open, and during the next repair if it is closed.

If there are chips, peelings or washouts of the protective coating on the surface of the wood, and they occupy more than 25% of the area, then the application must be repeated. Try to use the same product that you used before. If you bought something else, then you need to check the compatibility of these two substances. It’s better to remove the old fire protection layer altogether.

That's all. Impregnation of wooden structures may one day save your life. Try to be attentive. Good luck!

The main disadvantage of wood is its susceptibility to fire and biological decomposition. After 15 minutes of contact with an open flame (at a temperature of 230 degrees), the wood ignites. Lack of protection from moisture is enough for rot to begin. In accordance with the fire minimum, the fire resistance limit of a wooden structure must be at least 2 hours for load-bearing units, and 45 minutes for beams. To ensure this, it is necessary to carry out fire and bioprotection work using modern impregnations.

For the purposes of fire retardant wood treatment, we use the following types of fire retardant materials:

Surface fire-retardant impregnations are aqueous solutions of fire retardants (fire-retardant salts). Surface impregnations are used for fire protection of wooden structures in indoors, which do not involve the impact of precipitation on the surface of the wood.

Fire-retardant surface impregnations, with the introduction of antiseptic additives into them, solve the problem of preserving wood from fungus, mold, and insects.

Fire-retardant surface impregnations are a weakly effective method of fire protection of wooden structures. Surface fire-retardant impregnation only makes it difficult for flames to spread over the surface of a wooden structure.

Fire retardant impregnations fill the natural pores of wood with the dry components of the fire retardants included in their composition, thereby blocking the access of oxygen, protecting the surface from ignition. After fire retardant treatment, a wooden object is reliably protected from arson, short circuits and other factors that cause fire. Comprehensive fire protection also provides for the protection of wooden structures from natural natural factors- spread of mold and rot.

The peculiarity of the work is that all components of the combined fire retardant must be applied to the surface to be treated sequentially.

Fire retardant paints are suspensions containing fire retardants and other protective additives in certain proportions. After processing the wooden surface, a thin opaque film is polymerized on it. During a fire, the film is transformed into a coke layer, cutting off the supply of oxygen to the wood. Difficulty heating the wooden surface reduces the rate of fire spread, therefore, load-bearing structures will not lose their properties in extreme conditions. As a rule, fire retardant paint is white.

Pastes and coatings. The composition is similar to paints, however, the consistency is somewhat different - it is thick and coarsely dispersed. Such materials have no decorative value, since they are intended to create a thick layer on the surface of the wood. They are used where the risk of fire is especially high and decorative properties are not a priority.

Fire-retardant varnishes are film-forming solutions on an aqueous or organic basis. Unlike paints, varnish creates a transparent layer on the wood surface that does not hide the natural surface pattern, which is valuable from an aesthetic point of view. The quality of protection does not suffer - it corresponds to efficiency group 1. Typically, fire-resistant varnishes are used for indoor wood - walls, furniture, cladding, etc.

Fire retardant paint and varnish materials are the most progressive and effective means preventing the spread of fire and combustion. Unlike surface fire-retardant impregnations, they allow you to simultaneously obtain high-quality protective covering and provide decorative properties of the structure. A negative property of fire-retardant paints, varnishes and enamels is the high requirements for preparing the wooden surface, especially for the use of fire-retardant varnishes: the surface must be perfectly cleaned and sanded.

Combined protective compounds are a complex of several listed types of fire retardants, which have properties inherent in different types fire protection.

The procedure for carrying out fire protection work on wooden structures

1. Preparing the surface of a wooden structure.

In the course of preparing a wooden structure for fire protection work, the tasks of cleaning surfaces from old paint, old fire retardants, bitumen, oil and other contaminants, dust.

If it is necessary to apply fire retardant materials to a previously painted surface, a compatibility test of these materials must be carried out.

We clean the surface of a wooden structure using the following methods:

• Jet cleaning using soda blasting technology (Armex blasting). A highly effective technology that is similar in principle to sandblasting, but allows you to clean wood without damaging it.
• Sandblasting with fine sand, providing high-quality cleaning with minimal loss of wood.
• Manual and chemical cleaning using special reagents to remove old paint, oils, dust and dirt using hand tools.

Fire retardants Apply only to the prepared surface. Quality control of the prepared surface is carried out by a quality inspector. After receiving a positive conclusion, the surface is processed.

2. Application of fire retardants to wooden structures

Fire protection of wood (wooden structures) is carried out at a temperature environment not less than 10°C with a humidity level of not more than 70%. Fire protection work during negative temperatures are not carried out.

Fire retardant treatment of wooden structures is carried out when the humidity of the wood itself is no more than 15%.

Before applying fire retardant compositions, the compliance of the compositions with the physical and chemical indicators prescribed in technical conditions and quality certificate.

Fire retardant compounds previously applied to a wooden structure and not intended for removal must correspond in nature to the ph level with the fire retardant compounds intended for use, i.e. acidic compounds should be used with acidic ones, and alkaline ones with alkaline ones.

The application of fire retardant compounds is carried out mainly by airless method using airless application units.

3. Quality control of work on fire protection of wooden structures

Quality control of work on fire protection of wooden structures is carried out at all stages of the work by a quality inspector, who conducts an instrumental and visual examination to determine compliance with the permissible values:

• at the surface preparation stage the following is controlled:
  • Degree of surface cleaning;
  • Presence of dust on the surface;
  • Presence of oils and fats;
  • Surface moisture;
  • Surface ph level;
• At the application stage and after application of fire retardants, the following is controlled:
  • Wet layer thickness;
  • Dry layer thickness;
  • Coating continuity;
  • Coating adhesion;

Assessing the quality of fire retardant treatment is a separate operation. Monitoring the fire retardant properties of a wooden structure using special measuring equipment in accordance with the national Standard Russian Federation GOST R 53292—2009 "Fire retardant compositions and substances for wood and wood-based materials. General requirements. Test methods." Based on the results of the study, a test report is drawn up.

After the events internal control quality, fire protection work metal structures are submitted for quality of execution and compliance with the fire protection project to the Ministry of Emergency Situations, whose representatives are directly involved in the acceptance and signing of the certificate of completed fire protection work. Also, the quality of work can be confirmed by an accredited fire laboratory (IPL laboratory), which is not part of the Ministry of Emergency Situations.

There is currently a trend in construction towards a return to the use of natural materials. First of all, this concerns wood.

Wood is not only an absolutely environmentally friendly raw material, but also has many undeniable advantages.

It has only one drawback - it is defenseless against fire. But today this eternal problem, which caused a lot of trouble in the past, can be solved quite simply - by using a fire retardant composition for wood. By treating the material in this way, you can not only avoid a possible fire, but also protect it from other aggressive environmental influences.

Types of fire protection for wooden products

For processing the material there are special compounds, called fire retardants, which prevent combustion. Their effect on fire is that when heated, the fire retardant substance releases non-flammable gases and forms a film on the surface that blocks the flow of air to the wood. Thus, the ignition process is suppressed at the very beginning and further spread of the fire does not occur. In addition, the resulting film not only lowers the temperature of the material, but also absorbs excess thermal energy.

Such funds are divided into:

• Impregnations;
• Coatings.

The latter include various pastes, coatings, and varnishes. They are mainly used to protect wooden structures in attics and basements, since their use deteriorates the decorative properties of wood or is lost altogether.

Watch a video about the types of compositions:

Impregnating compositions practically preserve the wood texture and its natural beauty. They come in two types:

1. Organosoluble;
2. Water soluble.

The former contain unsafe solvents and are therefore not very popular. Water-soluble impregnations contain ammonium salts of phosphoric acid. They can be used either in pure form or in combination with other salts. An example is the combination of diammonium phosphate with ammonium sulfate. When the substance is heated, non-flammable ammonia begins to be released, and on the surface of the treated wood protective film, which consists of phosphorus oxide. A mixture of borax and boric acid also resists fire well.

Based on the effectiveness of fire protection, all means can be divided into two groups. The first consists of compositions, after treatment, with which the wood becomes difficult to burn. The second group consists of substances that make wood difficult to ignite.

On modern market Fire-retardant materials for wood, which simultaneously perform the functions of antiseptics and fire retardants, are especially popular. Their use makes it possible to fight not only fire, but also fungus.

Impregnation technologies at home

Applying a protective composition to wooden structures, carried out on your own, is possible using a brush or by spraying.

In this case, you should adhere to the agreed consumption rates. A fire retardant composition for wood processing purchased independently must have a certificate, which, in addition to its basic properties, also indicates the consumption standard.

It is very important that the impregnation performed does not lead to an increase in the hygroscopicity of the material and does not reduce its mechanical properties. One more an important condition, presented to this action, is environmentally friendly and safe.

If impregnation of wooden structures is carried out indoors, then compositions based on water based. Since they are easily washed out, it is assumed that the material is not exposed to moisture. For exterior work, the treated surfaces are additionally coated with a layer of varnish or paint.

When choosing a fire retardant compound used for wood treatment, you need to focus on the influence of the pH of the environment. There are many products on the market with the properties of concentrated acids, which can negatively affect the metal elements of the structures being treated and even pose a certain danger to consumers themselves when storing and using such substances.

Costs and their payback

The cost of modern compounds is quite reasonable. For example, treating one square meter of any wooden surface with a fire retardant substance will cost 20 rubles. If the composition also contains an antiseptic, then the treatment will cost several rubles more.

Mixtures used inside buildings, protecting wooden surfaces from fire and giving it a noble appearance, have higher prices. But it should be borne in mind that all costs incurred guarantee many years of fire protection. In this case, saving money is completely inappropriate, since thanks to the money spent you will save not only your property and house from violence fire element, but also ensure the safety of the people living in it.

Review of popular products

The domestic market is saturated with products from various manufacturers, both Russian and foreign. One of the most famous is the product “SENEZH OGNEBIO PROF”. This fire-retardant impregnation for wood, for which the price is lower than foreign analogues, and the quality is no worse, can not only protect the material from fire, but also prevents the development of mold and insects, and prevents rotting.

Used for processing:

• Rafters;
• Lathing;
• Sheathing;
• Beams;
• Stan;
• Floors.

Suitable for use in public, residential and industrial buildings.

Average validity period biological protection is 20 years, when the material is under the roof. The product allows wood to breathe and preserves its texture. Fire-retardant and bioprotective impregnation for wood NEOMID 450-1 significantly increases resistance wooden surfaces fire and serves as an effective antiseptic.

Treatment with this agent provides the structures with group 1 and 2 anti fire safety. At low consumption of the composition it useful action persists for ten years.

Watch a video about this product:

The impregnation is red in color, which allows you to control the uniform surface coverage and timely identify missing areas. Treating wood with this composition enhances its fire-resistant properties, turning it into a difficult-to-combustible material. An additional effect is high-quality disinfection of wood. Impregnation completely kills mold and fungi, protecting the material from being damaged by them in the future.

Fire retardant materials for wood processing of the BS-13 IZO® brand are considered one of the inexpensive and popular means. They are used to cover surfaces protected from precipitation. They serve as reliable protection from both fire and biological destruction. Recommended for application to rafters, beams, floors, walls, and attic cladding.

The drug not only transfers the material to a difficult-to-dispose group, but also reliably protects it from wood-boring beetles, mold and fungi. It can be applied to the surface using a brush or roller, or by spraying.

conclusions

Wood is a flammable material, which makes building construction it is fire hazardous. Undesirable consequences from their fire can be avoided by converting the wood into a fire-resistant material. This can be achieved by treating the surfaces by special means. Today, buying the necessary fire retardant composition is as easy as shelling pears; there is a huge selection on the market. First of all, they differ in composition and, naturally, in their effect on the material being processed.

The cost also varies and an expensive product is not always more effective than a cheaper one. It should be borne in mind that you often have to pay not so much for the quality of the product, but for the promoted brand; this mainly applies to foreign products.

Experts advise paying attention to the protection period indicated on the packaging. And, of course, for a certificate of conformity and fire safety.

Today natural wood They are actively used not only in the production of furniture, but also in construction, as it has been for many centuries. Wood is an excellent building material, but it has a serious drawback - it is susceptible to fire. Fortunately, fire-resistant wood treatments are now available to protect wood structures.

Protecting wood from fire is the main fire safety requirement for every building or structure, no matter during direct construction or during operation. Standards set out in local and regulatory documents, must be observed, otherwise the facility will not be put into operation. This is a mandatory condition for specialized construction organizations.

When building a private house, any owner must also provide fire protection for wooden structures; this requirement is not in vain.

Fire impregnation of wood is carried out at the following intervals:

• before putting the facility into operation;
• every 5 years;
• as necessary, if during operation the properties of the impregnation do not provide protection.

The latter can be checked very simply: you need to remove a small section of chips and set it on fire and, accordingly, if a fire occurs, treatment with a fire retardant is necessary.

Fire protection wooden base is a measure to ensure fire safety requirements that must be followed throughout the entire Russian Federation.

List of wood processing methods:

1. Performance finishing works using special fireproof materials.
2. Measures to increase the fire resistance limit.
3. Fire-retardant impregnation for wood using paint and varnish coating.
4. At the design stage, it is chosen which method to apply to a particular design. The inspection is carried out by a representative of the fire service.

Fire retardant treatment is required for the following elements:

• rafter structures (load-bearing and non-load-bearing);
• timber walls;
• coatings and floors;
• beams;
• shingles for plaster;
• wooden panels inside and outside;
• other wooden surfaces.

On video: fire retardant wood treatment.

Types of impregnations

The fire retardant composition for wood is selected based on the following parameters:

• Areas of use;
• appointments.

In total there are 3 types of impregnations against accidental fires or fires wood materials: acidic, alkaline, saline. In this case, specialized fire retardants, paints, varnishes or enamels are used for surface treatment of wood. After their application, a thin layer is formed. Water salt solutions used for deep processing of structural elements.

Although these methods are widely used in practical activities because of their effectiveness, but at the same time great success uses fireproofing treatment. It not only meets fire safety requirements, but also fully guarantees:

• provision high level protection;
• long-term processing efficiency;
• consistency in color choice;
• with almost everyone further coatings compatibility;
• safety for both nature and people or animals.

Acidic compounds

This is the best solution for impregnating wood against fire. In this case, the color of the material does not change, and its structure remains the same. The acidic agent provides additional strength to the structural element, while the wood “breathes” and fully retains its properties. A huge range of products is available in retail outlets.

Alkaline compounds

The effectiveness of using such impregnations is low due to the disruption of the wood structure, so they are not recommended for treating visible areas. Such compositions are commercially available and their price is low compared to acid solutions.

Saline solutions

These formulations are not as effective. After treatment, salt stains appear over time, which not only spoil the appearance of the tree, but it becomes necessary to carry out the treatment again. As a rule, for external work the validity period of such coating is no more than 2 years, and for internal work - no more than 5 years.

It’s easy to prepare saline solutions yourself; the only drawback is that you can’t calculate the proportions.

Fire-retardant impregnation of wood on any basis contains substances that melt when ignited, forming a thin film, which in turn creates an obstacle to oxygen. Impregnation compositions based on alkalis, when in direct contact with fire, produce gases to prevent the persecution or spread of fire.

A preparation based on urea or furan-urea resins has gained great popularity, since it provides not only fire resistance, but also direct resistance to the perception of mechanical loads.

Among other things, the fire retardant drug is divided into:

• resistant to external manifestations - for outdoor work;
• unstable to atmospheric factors - for interior work.

Today there is a whole range of fire retardants on sale, which provide fire protection properties.

Application of fire retardant paint

The very principle of impregnating wood against fire using the painting method is somewhat different from the direct effect of impregnation. Coating with antiseptic and fire-fighting compounds creates a layer to prevent heating and further fire of the structure. Once the wood reaches its combustion temperature, water and inert gases begin to be released. In addition, modern fire-retardant paints for wood have 2 functions simultaneously:

• from rotting;
• from fire or elevated temperatures.

Fire retardant paint is applied to the surface using rollers, brushes or a spray gun. The very frequency of wood processing fire retardant coating indicated by the manufacturer on the packaging, and even reaches up to 10 years.

Operating principle of wood fire protection:

Wood compositions that provide fire protection are easy to select in a store, according to the manufacturer’s specifications.

Properties of fire retardant varnish

This paint material has all the properties for fire protection, as well as its functional purpose - for decorative application. When choosing this product and using it, the structure of the wood is preserved.

Fire-resistant varnish impregnation is used not only for processing the wood from which the structure is built, but also for coating furniture, wooden floors, laminate and other surfaces.

The main properties of this varnish include the following:

• the composition for wood ensures the fire resistance of the structure for a period of 6 to 10 years;
• Can be applied to a previously painted surface, except for a pre-applied water-based coating;
• Work with fire-resistant varnishes must be carried out at a temperature of at least +5 degrees;
• wood treatment after application increases fire protection;
• Fire protection varnish can be matte or semi-matte.

This fire-bioprotective impregnation is fully compatible with non-expanding materials. In this case, there is no need to additionally apply a layer of antiseptic.

additional information

Wood processing is necessary, and there is also other important information about this:

• Fire retardant materials for wood, despite their relatively high price, quickly pay for themselves, especially since their consumption per 1 m2 is not so high. This characteristic is indicated by the manufacturer. In addition, it also contains an antiseptic.
• The drug intended for processing must have a certificate of conformity.
• Fire retardant treatment at enterprises is carried out by specialized organizations.
• The layer impregnated with a fire retardant composition will last a long time.
• The resulting fire will not affect all structures.
• The purchased drug should not be skimped on when applied, otherwise the desired effect will not be ensured.

Fire protection of wood. Experiment (1 video)

Despite the diversity modern materials, wood remains popular among our compatriots. But there is one negative nuance: the wooden covering can be destroyed due to fire. For this reason, it is necessary to treat wooden structures with a fire retardant compound (also called a fire retardant).

The principle of operation of fire retardant materials is based on physical and chemical processes that occur with the components that make up fire retardants. The main components of fire-fighting compounds are:

• fusible substances ( saline solutions boric, phosphoric or silicic acids);
• substances that emit gas (ammonia or sulfur dioxide).

When fusible substances are heated, a film appears, thanks to which oxygen cannot reach the surface of the wooden covering. As a result of this process, the ignition temperature of wood increases. This improves the fire resistance of the material.

Due to the use of gas-emitting substances, the combustion process itself is suppressed. The non-flammable gas protects the wood from fire by removing oxygen from the surface.

Fire retardants are divided into:

• coatings;
• impregnation.

There are the following features of the use of the material:

• varnish can be applied to a painted surface (with the exception of water-dispersed compositions);
• the process is carried out at temperatures above +5ºС;
• application of several layers of varnish occurs at intervals of at least 12 hours;
• The frequency of varnishing wood is 6-7 years.

The only nuance that should be taken into account when purchasing paint and varnish products is their intended purpose. Suitable for outdoor use only facade materials, which are characterized by increased wear resistance and fire protection.

Alternative options

In addition to impregnations and paints and varnishes, the fireproof properties of wood can be improved by using:

• materials used to create fire-resistant lathing;
• other constructive solutions.

Among the fire-retardant materials, gypsum fiber sheets should be noted. Due to the non-flammability of the material, the influence of heat on load-bearing structure. But there is a condition - all profile elements must be treated with a special solution. It is most advisable to use gypsum fiber only in cases where it is impossible to apply a fire retardant composition.

Application of rolled fire-fighting material (foil insulation) - best solution for fire protection of wood located in hard to reach places (attic floors, attic, other rarely visited rooms).

A constructive solution is the creation of a fire-resistant belt (or better yet, several), which will become an obstacle to the spread of fire. Places with the greatest likelihood of a fire are identified. After which fire-resistant belts are created near them. In some cases it is better to use plaster mixture with vermiculite or additionally build a reinforced brick frame.

Conclusion

You can check the quality of wood processing by:

• visual inspection of the structure;
• selective examination of the integrity and thickness of the layer of several sections.

Tests using fire are carried out using PNP-1 sensors. Based on the results of the research, acts are drawn up that authorize the operation of the facility.

You can check the quality of the fire retardant layer yourself. For this:

• a sample up to 1 mm thick is cut from the treated area with a knife;
• using a lighter, the sample is ignited on the side where the fire retardant is applied;
• the workpiece should not support combustion or smolder;
• after 20-30 seconds, the surface of the sample will blacken and char (without the appearance of a flame).

For comparison, you can take a piece of wood that has not been treated with a fire retardant. When you turn on the lighter, after 4-5 seconds the workpiece will begin to burn.

Naturally, the combustion process directly depends on the type of wood. For example, oak chips are difficult to set on fire even without impregnation. For this reason, all inspections are carried out on the basis of pine wood, which is highly flammable.

Video about treating a wooden structure with a fire retardant compound: