Wood varnish for outdoor use: varieties and technology of application to the facade

Varnish for outdoor woodwork is designed to protect products that are used outdoors from negative factors: ultraviolet light, pests, high humidity. Accordingly, the choice and application of compositions should be given special attention, because in stores they are presented in a huge assortment. How to choose and correctly apply wood varnish for outdoor use , we will talk in this article.

How do compositions for outdoor use differ from varnishes for indoor?

Today there are many compositions for coating wooden surfaces, but varnishes have one serious advantage - they allow you to preserve the unique and inimitable structure for which this natural material is valued.

Paints and varnishes (LKM) are divided according to several criteria, one of which is the conditions, in which wood will be used.

Products that are in the open air are exposed to weather factors, due to which the tree constantly swells and contracts. Varnishes designed for external surfaces form an elastic film on the surface of the material, which allows the wood to withstand regular swelling and drying. Indoor surface treatment compounds do not have a sufficient degree of elasticity, so the film will quickly crack and begin to lag.

Varnishes for outdoor use are used to cover the following elements:

• wooden steps, terraces, porch;
• parts of the roof;
• facades of wooden houses;
• bath walls;
• wooden sculptures and garden furniture ;
• entrance doors.

Compositions that are intended for such purposes should reliably protect surfaces from negative factors, mechanical damage, and also have good decorative qualities.

Characteristics of varnishes for outdoor use

In essence, all varnishes are mixtures of substances that are capable of forming a protective film on the surface of the material. To extend the life of wooden products, the composition for outdoor use must have a number of important characteristics.

1. Wear resistance. If the varnish is planned to be used to cover fences, walls or other vertical surfaces, for the sake of economy, you can choose a composition with an average wear resistance. For steps or terraces that are prone to rapid abrasion, you should choose products with increased resistance to mechanical damage and wear.

   

   Terraces need the most wear-resistant varnish

2. Drying time . Usually, the time for complete drying of compounds for outdoor woodwork depends on the substrate and is approximately 24-30 hours.An alternative is quick-drying paintwork materials that allow you to finish the job in a few hours. It should be noted that the instructions usually indicate several points regarding the drying of the composition: the time to tack (the interval during which dust and small debris cease to adhere to the surface of the varnish), the drying time of the first layer required to apply the finishing layer, as well as the time to form a solid film ..

   .

   

   The varnish can dry up to 24 hours or more

3. Resistance to mechanical damage. Wood is a soft material, and products that are used outdoors require special protection.
4. Resistance to ultraviolet rays. Exposure to UV rays is the main cause of wear and tear of paint and varnish coatings, since when burned out, the composition quickly loses its protective properties.

   Accordingly, it is very important that the ingredients include additives that increase UV resistance.

   

   The wood is exposed to UV rays all year round, therefore the varnish should provide maximum protection.

5. Water resistance. Another "weak point" of wood products is the tendency to decay, so the varnish coating must repel moisture.

   

   The varnish must protect the wood from moisture

6. Fire safety.

   If the wood has not been previously treated with special substances that protect the material from fire, special attention should be paid to the fire safety of the composition. The same applies to surfaces located in areas with an increased risk of fire, or those operated in high temperature conditions.

Varnishes for exterior woodwork may contain pest-protecting agents, components that give surfaces a glossy sheen or matt finish, and much more.

Types of varnishes for outdoor woodwork

There are several types of paint and varnish compositions that are used for outdoor woodwork, and each of them has its own characteristics, advantages and disadvantages ..

. The choice of a specific product depends on the characteristics of the material, the operating conditions of the product, as well as the final result that must be obtained.

Oil based varnish

The basis of such products are refined, thermally processed oils, which give the compositions the necessary properties. The quality of the lacquer coating directly depends on the quality of the base, therefore, it is not recommended to save on products. The second component of such varnishes is synthetic or natural resins, and most of the compounds that are sold in stores contain just synthetics.

The drying time for the compositions is quite long, so it is better to carry out work on clear days at an air temperature above 10 degrees and average humidity.

Important: When applying an oil-based varnish, the wood surface may darken slightly.

Depending on the proportions of resin and oil, formulations are oily, bold and skinny. Exclusively greasy varnishes (2 parts oil and 1 part resin) are used for the treatment of external surfaces, as they are characterized by resistance to weathering.

Yacht varnishes and polyurethane varnishes are varieties of such compositions.

The first option is used for surfaces that are in constant contact with water. Yacht (urethane-alkyd) varnish creates an elastic film on the surface that maintains its integrity even when the wood shrinks or expands.

Important: the application of yacht compositions requires a mandatory priming of the surfaces and accuracy during work. The film that forms on the surface must be solid and dense. If moisture gets under it, the tree will begin to collapse from the inside and the product will lose its original appearance.

Video - Yacht varnish

Polyurethane varnishes

Polyurethane compounds are easy to work with , provide high quality coating even if the master does not have the appropriate skills They dry quickly and protect the surface well from abrasion, mechanical damage and ultraviolet radiation.

Video - Applying polyurethane varnish

Alkyd varnishes

Compounds based on alkyd resins and a solvent provide a stable, durable and reliable coating of products. It is not affected by household chemicals, so the surface can be cleaned by any means. The disadvantages of solvent-based varnishes include a long drying time (about 24 hours) and the ability to change the color of the wood - after processing, the material becomes yellowish. The most common alkyd varnishes are GF-166 and GF-177.

Varnish GF-166. The base of the composition is an alkyd glyphthal resin modified with natural oils, with the addition of an organic solvent and substances that accelerate drying. Forms a transparent glossy film on the surface of the products, the drying time of one layer is 48 hours.

Varnish GF-177. In composition and main characteristics, the varnish is identical to GF-166, but has a shorter drying time and requires careful preparation for work.

Video - Coating with alkyd varnish

Water-based varnishes

This type of composition is made on the basis of an aqueous dispersion (for example, acrylic) with a small amount of solvent. Thanks to this, they do not have a pungent smell and do not give off toxic fumes, and work can be carried out even indoors.Water-based varnishes have a wide variety of color palettes and can give the material any chosen shade without masking the unique structure of the wood. Surfaces treated with such compositions are not affected by fungi, mold and microorganisms, and have an attractive appearance.

Water-based varnishes are divided into two types: they can contain only acrylic (one-component compounds) or acrylic with polyurethane (two-component).

Two-component acrylic-based paints and varnishes have improved performance properties and are not susceptible to negative environmental conditions.

Video - Acrylic wood varnish

Technical characteristics of different types of varnishes

Important: alcohol formulations and nitrovarnishes are not recommended for outdoor use. Alcohol-based varnishes are suitable exclusively for restoration and carpentry work, and nitrovarnish are characterized by low water resistance and are quickly destroyed by ultraviolet radiation.

The following companies are among the most popular manufacturers of paints and varnishes:

• AkzoNobel (Holland);
• Tikkurila (Finland);
• Henkel (Germany);
• BASF (Germany);
• DuPont (USA);
• Senezh (Russia).

Prices for various types of varnishes for wood for outdoor use

Varnish for wood

Step-by-step instructions for applying varnish

Correct varnishing is the key to the reliability and durability of the finish.

The main point that must be taken into account before applying work is that paints and varnishes have some features and application conditions.

1. Stir well and shake well before use.

   

   Preparing the varnish for work

2. The varnish should be diluted depending on its type. Usually paintwork materials are diluted with solvents (for example, white spirit), with the exception of acrylic compositions, where only water can be added, as well as yacht varnishes, which are not recommended to be diluted at all.

   

   Thinner

3. When working, use protective goggles, gloves and a mask, even if it is done outdoors, and the paint and varnish material belongs to the category of non-toxic.

4. Optimum conditions for applying varnish are dry calm weather, the air temperature is not lower than 10 degrees (cold can significantly increase the drying time of the varnish). The optimum temperature for work is 15-35 degrees, and the humidity is no more than 80%.
5. To avoid getting into the composition of dust and small debris, which can ruin the coating, it is recommended to pour the varnish into a small container.
6. Before proceeding with varnishing, it is recommended to test the composition - to apply it on a small area in an inconspicuous place.

   

   Test the varnish in advance

7. If possible, the varnished surface should be protected from dust and dirt - most compounds dry out within 24 hours, but it takes several days to form a solid film, and sometimes at least a week.

The rest of the varnish can be poured into small bottles or cans (so that as little air as possible remains between the surface of the substance and the edge of the container), tightly closed and put in a dark place, the temperature is from 5 to 30 degrees. In such conditions, the composition can be stored for about a year.

How to determine the varnish consumption?

To correctly determine the amount of paint and varnish mixture that will be needed to process a certain surface area, you need to know the varnish consumption per square meter. This parameter depends on the technical characteristics of the material and the composition itself.

1. Wood type .

   Porous species (ash, walnut, oak, exotic wood) require more varnish consumption, in contrast to non-porous ones, which include maple, birch, aspen, cherry.

2. Grinding quality . Well-treated and sanded wood requires less composition, therefore it is recommended to prepare the surface to save varnish.
3. The viscosity of the varnish. The density of the paint and varnish material also affects its consumption - the thicker the composition, the greater the amount required to process the product.

   For this reason, when carrying out work, a solvent or water is added to the varnish.

4. Tools that are used to apply the composition. To reduce varnish consumption, it is important to choose the right application tool.

The average consumption of the paint and varnish mixture when applying the first layer is a liter per 8-10 sq. M.

, and when applying subsequent ones - a liter per 10-12 sq. m.

Stage one.Choice of tools

The varnish is applied using various tools, mainly with a brush, roller or spray gun. Not only the consumption of the composition, as mentioned above, but also the quality of the coating depends on the choice of the tool.

Brush

The cheapest, widespread and affordable option. Most often in stores you can find brushes with natural, mixed or artificial bristles. Natural brushes are best for oil-based paints and varnishes, but when working, you should squeeze out the villi well - they have the ability to pick up and hold varnish, so streaks and irregularities can form on the treated surface. Synthetic brushes provide a smooth surface and are practically not subject to wear. The blended bristles combine the strengths of natural and synthetic, and the brushes are ideal for outdoor use.

Roller

The tool is convenient for processing large areas: fences, facades, etc. Rollers for applying varnish are distinguished by the features of the working surface of the tool, the length of the pile and the size. Long pile can be deformed during operation, as a result of which the quality of the coating decreases. Large rollers reduce processing time, but are inferior in terms of convenience, since small rollers create a more uniform and dense film. The best option for outdoor use is a medium-sized tool with a long reinforced pile.

Spray gun

Spray gun or spray gun - the most convenient a tool for painting fences and facades, as it can be used to easily process hard-to-reach places. Spraying makes it possible to create a quality, smooth and uniform coating. Spray guns can have a different tank volume, engine power and performance - the higher these characteristics, the more expensive the unit, but it is not very convenient to work with budget models, as they quickly overheat and turn off.

Prices for paint sprayers

Spray gun

Stage two. Surface preparation

For better adhesion of paints and varnishes and the proper quality of the future coating, the surface should be well processed.

If you apply the composition to unprepared wood, the coating will quickly lose its attractive appearance, crack and peel off.

The old coating (if any) must be removed with an emery cloth, trowel or a blow dryer until it is clean and hard.

If there are cracks or cracks in the wood, they must be removed with a special putty.

Clean the surface of the product from dust, small debris and sand with sandpaper. If there are grease or resin stains Sanding should be carried out along the grain - this will prevent small fibers from picking up, and the wood will be as smooth as possible.

The surface must dry well before further processing.

Stage three. Primer

Primer, or coating of lumber with special compounds, some craftsmen do not consider a mandatory stage of processing, but there are several objective reasons for their use:

• the primer provides good adhesion of materials - others in other words, the varnish adheres better to the surface and adheres well to it;
• the surface after treatment with a primer becomes smoother, thanks to which the coating is smooth and aesthetic;
• the use of primers makes it possible to reduce varnish consumption and save money.

The primer composition is selected depending on the characteristics of the material and composition for the final coating. Alkyd primer well emphasizes the structure of wood and increases its wear resistance, water-dispersion compositions do not have a pungent odor and are non-toxic, and shellac ones are recommended for covering poorly dried and damp wood

When choosing a primer taking into account the characteristics of the finish coating, it should be taken into account that for paintwork materials based on polyurethane, it is recommended to choose formulations with a solvent content.

When using water-dispersion paintwork materials, it is best to take an acrylic or water-based primer. For outdoor use, it is recommended to choose formulations that additionally contain components that prevent the appearance of rot, fungus and mold.

The application of the compositions can be started after preparation (the process is described above) and thorough drying of the surface.

Step 1. Prepare the composition (dilute according to the instructions) and mix well him.

Pour it into a suitable container wide enough to dip your brush into.

Step 2. Apply the solution to the surface in an even layer by running a brush or roller along the grain of the wood. When processing a facade or a fence, pay special attention to the lower part, as it is most susceptible to moisture.

Step 3.

Allow the first coat of primer to dry well.

Step 4. To clean the dried layer with a "sandpaper", if the surface is uneven, use a putty on wood. Remove dust from the wood that has formed after sanding.

Step 5.

Apply 1-2 more over the first layer, each of them must be allowed to dry well.

After the primer has dried, proceed to the finishing - coating the product with a varnish mixture.

Prices for wood preservatives

Impregnation for wood

Stage four. Varnishing

Before varnishing the wood, it is recommended to carry out an adhesion test. Cover a small area of ​​the prepared surface with the composition, apply the composition, and after 2-3 days try to remove it with a coin or spatula.

If the coating is difficult to remove, then the varnish is well connected to the base. In the case when a coin or a spatula leaves clearly visible, deep marks, it is necessary to process the surface again or choose another varnish.

It is best to apply varnish on a horizontal surface, therefore, if possible, place the product vertically - for example, when processing doors, remove them from their hinges and put them on the trestle.

The process of varnishing wood surfaces

Step 1. Prepare the composition (if necessary, dilute it with water or white spirit), mix well, pour into a suitable container.

Step 2. Apply the first coat of varnish to the wood. Squeeze the composition onto a tool (brush, roller) slightly to avoid dripping. On horizontal surfaces, the varnish is applied in stripes, and on vertical surfaces - in cross movements, uniform and smooth. Some compounds (for example, acrylics) set almost immediately, so you need to work quickly enough so that no brush marks remain on the surface.

The varnish must be rubbed well and make sure that bubbles do not appear on the surface - they can be removed by brushing along the grain of the wood. When working, pay special attention to hard-to-reach places and corners.

Step 3. After applying the first coat, it must be allowed to dry. The drying time of the varnish differs for each type of composition: in the case of water-based paints and varnishes it is from 1 to 12 hours, for alkyd and polyurethane mixtures - 24 hours, so it is better to clarify it in the instructions for the product.

Step 4. Once the initial coating is dry, it is best to sand it with fine-grained emery - this way the second layer of varnish will adhere well to the first.

Step 5. Apply a second coat of the compound, this time undiluted, and let dry.

Step 6.

Assess the treated surface in good lighting, apply if necessary another 1-2 layers of varnish.

When using quality formulations and the correct application, two coats of varnish are usually sufficient for a good surface finish.

Tips for applying tinted varnishes

Tinted varnishes usually used to cover inexpensive types of wood.During processing, two tasks can be solved at once: to protect the material from damage and negative factors, and also to "refine" its appearance. The technology for applying such compositions does not differ from the application of conventional ones, but has a number of nuances.

1. After applying the first layer of varnish, the wood turns out to be matte even when using a glossy composition, since it is almost completely absorbed into the wood.
2. For very porous woods (eg pine) at least three coats of varnish are required.
3. To emphasize the structure of the wood, it must first be well sanded.

   

   Grinder for processing walls of a wooden house

4. Before applying the tinted composition, the surface should be primed not with an ordinary primer, but with a colorless varnish.
5. The color of the coating applied to the wood may differ from that shown in the catalog.

   

   Some shades of varnish

6. To obtain a lighter tone, the composition should be diluted with a thinner, and for a dark tone - apply at least three coats varnish.
7. The original color is not affected by acrylic varnishes, as they create a completely transparent film on the surface.

With the correct choice of the type of varnish and following all the rules for its application, you will get absolutely smooth, a well protected and aesthetically pleasing surface that will delight the eye for years to come.

Video - Neomid Interior. Wood varnish