- How to protect wood from moisture, insects and fungus
- DIY antiseptics
- Ready-made wood preservatives – types and characteristics
- Fire retardant paint for wood
- How to choose and use antiseptics and fire retardants
In this Article: Antiseptic Wood Preservatives how to make an antiseptic drug yourself; ready-made antiseptics – types and characteristics; recommendations for the selection and use of wood protection products.
The oldest, if not classical, material for the construction of any building on Earth was and remains wood. This building material is ubiquitous and abundant on our planet, thereby providing earthlings with a permanent construction material for creating houses and decorating them. However, wood is far from ideal – it is exposed to microorganisms and insects, ultraviolet light, it changes its volume depending on the degree of humidity inside the room and a series of warm / cold seasons outside the building, causing deformations in the building structure. Moreover, wood is flammable. What about the owner of a wooden house, really demolish it and build a brick or stone one? Not at all, you just need to timely process the wooden structures of the house with drugs that have antiseptic, moisture-proof and fire-retardant properties.
How to protect wood from moisture, insects and fungus
Any wood absorbs moisture like a sponge, which invariably leads to its decay. The ancient Greeks were looking for ways to protect wood from moisture, covering wooden buildings with a layer of olive oil. However, neither their method, nor the more modern one, which consists in painting wooden structures with several layers of paints and varnishes, did not give a long-term effect. There are two reasons for this: a layer of paint is only able to protect the wood from the outside, without affecting in any way the internal processes of decay (biological corrosion); any layer of paint will crack and crumble over time under the influence of the environment surrounding it, exposing the wood and giving moisture access to it.
Conventional paints and varnishes consist of a pigment suspension suspended in binders that form a film when applied in a thin layer to a surface. Such paints are capable of providing external protection to wooden structures only if they are correctly selected, based on the conditions in which this wooden building will be used, as well as with the timely restoration of painted areas in case of damage. More effective protection of wood is achieved when it is treated with antiseptic preparations (impregnates), which include biocides.
Wood processing with biocidal preparations is carried out by the following methods:
- antiseptic solution is applied with a paint brush;
- wooden surfaces are treated with an antiseptic by means of a spray;
- wooden structures are completely immersed in biocidal solutions, heated or not.
The most effective antiseptic protection of wood is achieved by industrial processing methods:
- by impregnation in an autoclave;
- keeping structural elements in steam-cold and hot-cold containers;
- diffusion impregnation, during which a pasty material with an antiseptic is applied to a wooden product and gradually penetrates into its structure.
As antiseptics, aqueous solutions of sodium fluoride and sodium fluorosilicate, copper and ferrous sulfate, as well as clay, extract, bitumen pastes and oil antiseptics (creosote, etc.) are used – their use increases the biocidal protection of wood, but they cannot be used for the color of wooden structures, i.e. not able to give them decorative qualities.
The most common impregnate among oil antiseptics is creosote – an unpleasant-smelling liquid, colorless or with a yellowish tinge, obtained from coal or wood tar. Creosote owes its popularity to railroad tracks – wooden sleepers were impregnated with it. This antiseptic does not have a corrosive effect on metals, but gives the wood impregnated with it a dark brown color. Creosote is poisonous (contains phenols), so homeowners who use “free” old sleepers in the construction of houses and summer cottages are making a big mistake.
Sodium fluoride– white powder with a grayish tint, the highest solubility in hot water is 3.5-4.5%. It has high antiseptic properties, penetrates well into the structure of wood, does not corrode metal. Sodium fluoride is toxic to insects and fungi, dangerous to animals and humans. It should be borne in mind that upon contact of sodium fluoride in dry and solution form with chalk, lime, alabaster and cement, it loses its antiseptic properties, i.e. ceases to be poisonous to insects and fungi – reacting with calcium salts, it passes into a stable state that does not allow it to dissolve in water. To draw up an antiseptic solution, water with a low content of lime salts (soft water) is required – river or rain.
Sodium fluorosilicateis a white powder with a gray or yellow tint, slightly soluble in water – no more than 2.4% at a temperature of 100 ° C. It has significantly lower antiseptic properties in comparison with sodium fluoride, because slightly soluble in water. The toxicity of sodium fluorosilicate increases if its aqueous solution is introduced technical ammonia, soda ash or other alkaline substances, as a result of reaction with which it forms an aqueous solution of sodium fluoride.
Copper sulfate (copper sulfate)in dry form it looks like blue crystals. Solubility in water 28%, the antiseptic effect is much weaker than that of solutions with sodium fluoride. In addition, the copper sulfate solution has a strong corrosive effect on ferrous metals – this antiseptic can not be used on wooden structures containing any iron fasteners.
Dry ferrous sulfate (ferrous sulfate)looks like green crystals. Let’s well dissolve in water – up to 25% in cold, up to 55% in hot. Possesses weak antiseptic properties, similar to the biocidal action of copper sulfate solution, and does not corrode iron.
Biocidal pastesare made of several components – a water-soluble antiseptic (sodium fluoride or fluorosilicate), a binder (liquid glass, bitumen, clay, etc.) and peat powder as a filler. Due to their visibility after being applied to wood, such pastes are used to protect hidden wooden elements – buried ends of poles, beams, etc..
In the presence of chemical reagents, you can make up an aqueous solution of the impregnate yourself, using soft rain or river water:
- based on copper sulfate (copper sulfate) or ferrous sulfate (ferrous sulfate). In the first case, the consumption of the reagent is 100 g per liter of hot years, in the second – 150 g per liter of hot water;
- based on sodium fluoride. Consumption of 100 g per liter of hot water;
- based on table salt and boric acid. Dissolve 50 g of boric acid and 950 g of sodium chloride in 5 liters of boiling water, treat the wood with this composition 2-3 times. The effect of protecting wood will be short-lived, but it will still be possible to double the service life of wood products..
The sides of wooden posts that will be submerged in the ground can be protected from rotting by soaking them in a biocidal solution..
Attention: without exception, all biocidal preparations designed to protect wood from the effects of insects and fungi are extremely toxic to humans, you can work with them only in durable rubber gloves, you will need protective glasses and a respirator!
A 20% aqueous solution of copper sulfate is prepared in a wooden or plastic barrel (the container is half filled with water), the pillars are immersed in it with the side that will be buried in the ground. The pillars must be kept in a biocide solution for at least 48 hours, then they must be removed from the solution and placed under a canopy for a month, while the sides of the pillars soaked with an antiseptic should be at the top.
Ready-made wood preservatives – types and characteristics
The above-described aqueous solutions of biocides provide protection of wood from various types of fungus and insects, however, such impregnation is not able to protect itself from being washed out by moisture coming from the outside – for full protection from precipitation and ultraviolet radiation, special factory-made preparations are required. Such ready-made impregnations with impregnates are subdivided into systemic – ground, covering and glazing – and complex, i.e. having the qualities of three systemic drugs at once.
The purpose of the system impregnations is as follows:
- antiseptic wood primers containing little or no pigment are designed to be deeply absorbed into the wood structure. As a rule, they are sold in a concentrated form and diluted with water in a certain proportion. The average cost of a liter of biocidal primer is 350 rubles;
- covering antiseptics provide protection of wood and, at the same time, are able to retain their color regardless of the original color of the surfaces to which they are applied. If necessary, dilute them with water. The cost of 0.9 kg of a covering antiseptic is about 470 rubles;
- alkyd-alcohol based glazing antiseptics are used for biocidal protection of wood, and also provide high protection against moisture, forming after the application of the second layer a strong protective film, the thickness of which exceeds that of conventional varnishes. Dissolved with white spirit, initially transparent, tinting to a certain color shade is allowed. The average cost is 320 rubles. for 0.9 kg.
Complex preparations for wood protection, according to the characteristics declared by the manufacturers, are a covering stain, impregnation, water repellent and, most often, a fire retardant. However, the protective characteristics of such products are questionable, because each of the specialized systemic impregnations is applied separately and each of them penetrates the wood structure to the greatest depth, thereby providing maximum protection. But the complex preparation must simultaneously impregnate the tree with a biocide, paint it and provide protection from moisture, which will not be done equally well, because too many additives. Accordingly, the service life of the complex coating is very short. Most complex antiseptics are water-soluble, their cost per liter ranges from 90 to 300 rubles.
The largest foreign manufacturers, whose wood paint is also designed to combat biocorrosion: Tikkurila (Finland), Selena (Poland), Alpa (France), Akzo N. V. (Netherlands), “Belinka Belles” (Slovenia). Among domestic manufacturers, it is worth highlighting the products of LLC “Ekspertekologiya”, CJSC “NPP Rogneda”, LLC “Senezh-preparations” and FSUE SSC “NIOPIK”.
Fire retardant paint for wood
With all its structural advantages and environmental friendliness, wood burns perfectly and supports combustion, which means that wooden buildings need additional strengthening of fire retardant properties.
Fire retardants that reduce the flammability of wood are produced in the form of impregnations, varnishes and paints, divided into two groups according to the principle of action:
- blocking the access of flame and heat to wood. Such fire retardants act like a fire extinguisher – direct contact with an open flame causes them to swell with the formation of a foam layer on the surface of wooden structures;
- preventing combustion by emitting gases. Contains salt, fire resistance mode is activated upon contact with fire.
In case of fire, fire retardants of the first group should create a finely porous foam that retains its insulating properties at high ambient temperatures. Foaming of such fire retardant compositions is caused by organic amines and amides, which at high temperatures form gases – nitrogen, ammonia and carbon dioxide, swelling a softened coating consisting of resorcinol, dextrin, starch, sorbitol and phenol formaldehydes. Stabilization of the foamed coating is achieved by introducing metal oxides, perlite and aerosil into their composition.
Fire-resistant coatings in the form of paints, varnishes and coatings, which are usually used to protect metal structures, are not capable of providing fire protection for wooden structures, because prolonged exposure to high temperatures causes them to detach from surfaces and exposes the wood, allowing an open flame to reach it.
The greatest protection against fire for wooden structures is provided by impregnation with fire retardants, penetrating into the structure of the wood, filling its pores and enveloping the fibers. Such impregnating compositions are colorless, contain water-soluble salts that melt when heated and envelop the wood surfaces with a film that protects against direct contact with fire or emitting non-combustible gases in a large volume that block air access to the tree.
According to the depth of penetration into wood, impregnations differ by:
- superficial (capillary), penetrating into a tree at a depth of no more than 7 mm. It is applied by brush or spraying, its introduction does not reduce the strength characteristics and does not cause internal stresses in the wood structure. Since the depth of penetration of such impregnations into wood is small, it is necessary to use reagents with a high degree of fire protection at low consumption;
- deep, the depth of penetration into the wood is at least 10 mm. The efficiency of deep impregnation is higher than that of surface impregnation, in addition, it allows you to preserve the texture of the wood. However, its fire retardant properties are provided by a significant amount of fire retardants, which leads to an increase in the weight of wood and a decrease in its strength characteristics. Deep impregnation is carried out in the factory under pressure, autoclave-diffusion method and in hot-cold baths.
In terms of the degree of fire protection, fire retardants are most effective, which include orthophosphoric, tripolyphosphoric and pyrophosphoric acids, as well as sodium salts – polyphosphates, tripolyphosphates and sodium dihydrogen phosphate.
Salt fire retardants based on various combinations of ammonium sulfate and chloride, diammonium phosphate, phosphoric acids, urea, sodium fluoride, etc. are most widely used on the Russian market for fire retardant materials. The ingredients for such fire retardants are inexpensive, their aqueous solutions are easy to prepare, and after the water evaporates, their constituent components form a reliable fire retardant layer..
According to the results of mandatory certification, fire retardant paint is divided into three groups:
- Impregnations of the 1st group modify the wood to be resistant to combustion, i.e. the loss of mass of the processed wood sample does not exceed 9%;
- treatment with fire retardants of the II-nd group allows obtaining fire-resistant wood, the mass loss of which during ignition is no more than 25%;
- the III group of impregnations includes those compounds that have not passed the tests and are not fire retardant.
On the domestic market, fire retardants of domestic production are widely represented, their cost depends on the certified group – drugs of the 1st group cost an average of 250 rubles. per kg belonging to the II-nd group will cost the buyer about 40 rubles. per kg. As a rule, manufacturers of biocidal preparations simultaneously develop and manufacture fire retardants, therefore impregnation of the above-mentioned Russian companies are also presented on the market, including LLC Gothic, LLC Senezh-preparations, LLC Ekspertekologiya and ZAO NPP Rogneda.
How to choose and use antiseptics and fire retardants
When choosing a wood preservative, it must be borne in mind that preparations of this group are not universal and are designed for a certain degree of biocorrosion. They differ in the degree of damage: wood without signs of activity of insects and fungi; defeat in the initial stage; deep defeat. Based on the current situation with wooden structures, drugs and their concentration should be selected. External surfaces should be treated only with systemic preparations, the latter of which should provide guaranteed protection against ultraviolet radiation and precipitation.
If you need to provide biocidal protection of the bath or sauna premises, then such treatment should be carried out with the preparations of only one company – the Finnish Tikkurila, the only manufacturer that guarantees the safety and effectiveness of its products in the harsh conditions of a sauna and a bath.
When choosing a fire retardant impregnation, pay attention to the conditions in which its operation is allowed. As a rule, there are preparations on the market intended for indoor use, i.e. the surfaces treated with them should not be affected by atmospheric moisture, which will certainly wash out the fire retardant. To protect against moisture, the surfaces treated with a fire retardant are covered with a layer of varnish, therefore the fire retardant agent, which is supposed to be applied to wooden walls from the outside, must form a layer with good adhesion of paints and varnishes.
An important consideration when choosing a flame retardant will be the pH level of the drug. Fire retardants are produced with a hydrogen ion concentration (pH) of 1.5, which is almost the same as that of concentrated acids. Such fire retardants are extremely dangerous for humans, their use and storage require a number of special conditions. In addition, drugs with a high pH value are extremely aggressive on ferrous and non-ferrous metals, actively corroding them up to serious destruction..
Before purchasing, be sure to make sure that this antiseptic or fire-retardant drug is safe for households after it dries – the corresponding information should be present on the impregnation package. I repeat – information about the safety of an antiseptic and a fire retardant refers only to its operation after application and drying, in the process of work, any such drug is extremely dangerous to humans!
Work with antiseptics and fire retardants is carried out only in rubber gloves, a body-covering overalls, a respirator and goggles. Before starting processing, wooden structures must be cleaned of dirt and dust, remove the resin and the old paint and varnish layer, if necessary, sand the surfaces with sandpaper. The impregnation is applied in two layers, if a systemic treatment is used, then each preparation is applied in two layers. All depending on the service life declared by the manufacturer, it is better to re-process it every year or two. And yet – there are no drugs that can provide biocidal protection from one treatment for many years.!
In conclusion: you should not rely on fire retardants as some kind of final remedy for a fire – in case of fire, households of a wooden house treated with high-quality fire protection agents have 30 minutes, during which they must extinguish the fire on their own or wait for the arrival of firefighters.