Wood varnish - what are the requirements for it?
In fact, varnish is a solution of substances capable of forming a protective layer on the surface to be treated as a thin film. It would seem, what kind of choice can we talk about? You can take any varnish and "protect" the wood. However, everything is not so simple, because coating the wood with varnish, which is picked up incorrectly, can do more harm than good. Only after taking into account all the nuances can we talk about the selection of a really good varnish. So, the main selection criteria are:
- Wear resistance. On sale there are varnishes, differing by an increased index of resistance to wear. As a rule, they are used to protect floor coverings, which are under heavy loads from constant walking and friction. If you do not need additional wear protection, then you can choose the usual composition.
- Drying time. Here the choice is between the traditional compositions, the drying time of which can reach 30 hours, and their alternative - quick-drying varnishes, allowing you to manage the work in one evening. The greatest drying time is noted for water-based formulations, and the lowest for nitrolacs.
- Toxicity. Most of the currently available varnishes( polyester, acrylic, polyurethane) are characterized by an unpleasant, pungent odor, thanks to the solvents content. When they are used in a living room, you risk getting a headache for a few days. In this case, an odorless varnish for wood, for example, water-based, is preferable.
- Degree of gloss. You can buy a composition that gives the surface of the wood a nice glossy gloss, or makes it matte. When choosing it is recommended to be guided by your own preferences and the degree of gloss on the surrounding surfaces.
- Fire safety. Select varnishes for wood and depending on how much the surface to be treated is exposed to high temperatures. If wood is used in a room where there is a high risk of fire, you should purchase a heat-resistant varnish that does not support combustion.
- Number of main components. Today it is customary to talk about one- and two-component varnishes. In the first case, the protective film is formed as a result of evaporation of the solvent and complete drying of the residue. In the second - the film is the result of a chemical reaction between the solvent and the hardener. Such two-component varnishes are called professional because they provide the highest quality of the protective film.
In addition, it is recommended to pay attention to whether the lacquer is applied directly to the wood( self-priming) or requires additional processing. This is not the main criterion for choosing the composition, as the first variant is most often found on sale, but it is impossible to bypass it. Of great importance is the quality of wood, the degree of its porosity, for example. This is important, since pine varnish is not suitable for birch processing, etc. Moreover, the quality of wood is directly related to such an indicator as the consumption of wood varnish.
Wood varnish for outdoor and indoor use - what's the difference?
The degree of exposure to external factors is one of the main criteria for choosing a varnish. So, if a product made of wood or a wood surface is located in the open air and is exposed to all atmospheric phenomena, exposed to UV rays, it is recommended to purchase varnish for outdoor work. It allows the wood to withstand multiple cycles of moistening-drying, freezing-thawing. The use of varnish for internal work in this case will lead to rapid cracking of the wood, yellowing and abrasion of its surface.
Specialists note that wood varnish for outdoor work must necessarily include in its composition substances that protect the surface from UV rays and prevent the formation of mold on it!
A distinctive feature of such compositions is a high degree of elasticity of the protective film, which allows it not to break down with allowable deformations of the wood. Unlike varnish for exterior work, the composition for internal work should be less elastic. The film formed by it should be characterized by a high degree of hardness and strength. Thus, the competent selection of varnish, depending on the intensity of external influences, directly affects the durability and aesthetics of the wooden surface.
Varnish for wooden floors, walls, furniture and other surfaces - choose according to the composition
One of the main criteria is the varnish composition, which determines its performance properties and characteristics. The main types of wood varnish today are: alkyd, alkyd-urethane, oil, acrylic, epoxy, polyurethane and nitro-lacquers. Each species has its advantages and disadvantages. The most widespread alkyd formulations, based on organic solvents and alkyd resins.
They are perfect for interior work, are able to withstand the impact of moisture, form a durable and reliable coating. Essential disadvantage is only the time of drying, reaching 72 hours! To reduce its allow additives, hardeners, but in this case for a complete drying will need a day. By adding urethane groups to alkyd resins, alkyd-urethane varnishes are obtained which differ from alkyds with high resistance to wear and a shorter drying time - about 6-12 hours.
Oil varnishes are also well suited for interior work, in particular for the primary processing of wood and giving it a particular shade. The color palette is rather wide - from light yellow to saturated brown. Depending on the amount of oil, it is customary to talk about fatty( 65-85%), medium fat content( 55-65%) and lean( 30-55%) formulations. Oily varnishes perform both functions - protective and decorative, but skinny ones are suitable only for making the wood aesthetic.
Nitro-lacquers( nitrocellulose) are considered to be fast-drying. It takes only a few hours to completely dry them. In addition, they easily penetrate into the pores of the wood, completely filling them and providing an excellent quality of surface protection. Nitro-lacquers have a high degree of strength and good moisture resistance, but they can harm human health, because they contain toxic solvents in their composition. That's why when working with them, special measures of respiratory protection, in particular, a respirator, are necessary.
One of the most environmentally friendly and safe is the acrylic composition on a water basis. It does not burn, provides high strength and elasticity of the coating, perfectly preserves the texture and natural shade of the wood surface. The coating is transparent and lacks an ugly yellow shade, can have a different degree of brilliance. However, the drying time of acrylic lacquer directly depends on the microclimate of the room in which it is used. Moreover, experts say that to fully form a quality protective film you will need to wait 10 to 14 days! It is not recommended to use acrylic composition on a water basis in rooms with high permeability or humidity.
Epoxy varnishes are quick-drying, as their drying time usually does not exceed 12 hours. They are perfect for outdoor work, as they are resistant to moisture, mechanical damage and chemical influences. Polyurethane varnishes, characterized by high strength, resistance to moisture and abrasion, have gained wide popularity. These properties allow using this kind of composition on almost any wooden surfaces. Ideal for protecting parquet, emphasizing its aesthetics. Thus, competent selection of varnish for wood is a guarantee of its beauty, durability and practicality.