Wood primer for interior and exterior work – what are they and how to choose?

Whether you’re working on an exterior construction project or an interior renovation, selecting the proper wood primer is essential. Any paint job starts with wood primer, which makes the final coat look smoother and last longer. It assists in sealing the wood’s porous surface to stop moisture from soaking in and causing damage over time.

Wood primers come in a variety of forms, each intended for a particular use. For interior painting, you may want to use a primer that acts as a stain barrier and gives paint a consistent surface. Conversely, exterior primers are designed to endure inclement weather and provide defense against precipitation, snow, and ultraviolet radiation.

Think about things like the kind of wood you’re working with, the environment it will be exposed to, and the type of paint you’ll be using when choosing a wood primer. Water-based primers are more ecologically friendly and easier to clean, but oil-based primers work well at sealing knots and stopping tannin bleed. Gaining an understanding of these distinctions will enable you to decide wisely and complete your project with the greatest outcomes.

Type of Primer	Usage
Oil-Based Primer	Great for blocking stains and sealing porous surfaces. Suitable for both interior and exterior wood.
Water-Based Primer	Easy to clean and quick drying. Ideal for interior wood surfaces and works well with latex paints.
Shellac Primer	Excellent at blocking odors and stains. Can be used for both interior and exterior wood but is more commonly used indoors.
Stain-Blocking Primer	Specially formulated to cover stains from water, smoke, and tannin bleed. Suitable for both interior and exterior applications.

What is it – wood primer

When it came to working with wood, everything was clear and easy until recently. Fire retardants, rotting, the development of mold and mildew, and the infestation of wood-boring insects (which are usually drying oil) are all prevented by an impregnation applied to the material. Additionally, a primer is applied prior to painting or plastering in order to enhance the paintwork materials’ and solutions’ adherence to the base, which is wood. This, incidentally, is the traditional goal of all primers.

These days, not even seasoned experts, let alone do-it-at-home craftspeople, can quickly identify what is displayed on store shelves in retail chains. Manufacturers’ desire to streamline and expedite the technological process of processing wooden products gave rise to the issue. They combined two types of impregnation or impregnation with a primer to achieve this. Hence, the 2 in 1 writing might suggest that the mixture of fire retardants and bioprotectants is combined with a primer, and that this is the composition of the solution. When the canister reads "3 in 1," it makes things simpler because the solution already includes the three parts of protection.

Wood primer composition

Current wood primer compositions include the following:

• various oils – penetrate deep into the wood, preventing the access of moisture and air. Well-impregnated wood practically does not change its linear dimensions under the influence of temperature and humidity (adhesion to paint or plaster is maintained) and does not rot;
• resins – level the surface, allowing to significantly reduce the consumption of paints and varnishes during painting;
• glue – improves adhesion to paints and plasters;
• pigments – reveal the beauty of natural wood, giving it an accentuated color. Most often, such a primer is used for finishing;
• asidol – a liquid mixture of naphthenic acids. The main type of wood antiseptic. The composition of the primer may also include other types of bioprotective solutions;
• fire retardants – chemical compounds of mineral origin that reduce the flammability parameters of the treated material (most often boron).

Impregnation functions

You must be aware of the purposes of impregnating compounds in order to decide whether priming wooden structures is required and how to do it. Many of them:

• protection from adverse biological factors. Wood as a building material has many enemies:

1. moisture – promotes the development of putrefactive processes, the appearance of mold and mildew;
2. rodents – they like to make moves and eat in the absence of food supply;
3. wood-boring insects – damage wood from the inside. Can completely destroy a product or structural material of a building;
4. high temperature – prevents cracking during drying. Moisture is clogged inside the wood fibers, and therefore there are no changes in linear dimensions, and, therefore, there are no reasons for the formation of cracks.

• improvement of adhesion with varnish and plaster compositions;
• increasing the strength and hardness of the top layer. Wood, with rare exceptions, is a soft material. Therefore, it is not difficult to scratch or leave a dent from a sharp heel. Resin helps prevent such defects. Penetrating deep into the material, it glues the fibers together, preventing their delamination;
• reduction in the volume of absorbed materials. The structure of wood fibers is such that it actively absorbs not only moisture, but everything in a liquid state, including paint and varnish. Primer allows you to reduce paint consumption. At the same time, it acts in two directions: it closes micropores, preventing absorption, and creates a smooth surface, as a result of which the paint does not fill the smallest depressions on the surface;
• increasing the durability of wooden structures and products, which is natural – a barrier has been created against unfavorable factors that have a detrimental effect on wood;
• increasing the practicality of the material – it is easier to remove dirt from a smooth surface. This is especially important if there is a risk of spilling coffee, tea, or wine. Such stains can only be removed from untreated wood with a plane;
• preservation of natural color. The applied protective film prevents tannin from coming to the surface – a coloring substance that ages wood, darkening under the influence of ultraviolet rays;
• protects from fire – ignition either does not occur (the wood simply chars without ignition) or is delayed for 15-25 minutes. Let us remind you that wood begins to burn at a temperature from +460 to +885 o C (depending on the density of the wood, which is different for different tree species);
• preserves the texture and color of natural wood.

Pros of priming

Using impregnation for wood treatment enables you to:

• extend the service life of building structural elements;
• increase surface strength;
• improve adhesion between the wooden base and paints or plaster;
• protect from adverse weather factors: rain, sunlight, temperature changes;
• prevent the appearance of fungus, mold, and the infestation of wood-boring insects;
• level the surface;
• reduce paint consumption when painting;
• give a more aesthetic appearance.

In what cases is it necessary to prime wood

Not everything is clear when using priming wood. Online materials do not advise against impregnating every structural element of a wooden building; rather, they point out that doing so is essential. For instance, it is required in certain former Soviet nations to impregnate the rafter system with fire retardants. However, you don’t need a primer. Paint, for instance, will handle its functions just as well. However, you also need to consider other factors.

Enamel, for instance, causes the wood’s fibers to rise; the surface is not smooth. Before adding the second layer, you will need to manually sand the entire surface with sandpaper or use a grinder. Primers are easier to use and less expensive to impregnate. Pretty much the same with every kind of paint. Buying a primer is not as expensive as abusing it. When applying plaster mortar, a primer is an absolute necessity.

There’s good ventilation in the rafter system. Therefore, durability won’t be significantly impacted by poor treatment in cities. A forest or park with coniferous trees close by makes all the difference in the world. Wood-boring beetles can easily settle under the roof of a newly constructed home (as has been repeatedly observed), either as a result of ignorance or greed on the part of the owners who neglected to prime the surface. Controlling pests is pointless. Replacing the entire rafter system is simpler. In conclusion, surface priming is required here as well.

The consequences of leaving the soil untended were candidly explained by the editors of the StroyGuru website. The owners will determine whether or not to perform this technological operation.

Types of primers

Primers can all be categorized:

• by composition;
• purpose;
• functional features;
• Areas of use;
• blossom.

By composition

Every primer is based on a distinct material, either mineral or synthetic:

• acrylic;
• alkyds;
• silicone;
• latex;
• drying oil;
• shellac;
• epoxy resin.

Primer made of acrylic. Various ingredients can be used in impregnation based on acrylic (polymer of acrylic acid):

• water – allows you to obtain a water-emulsion dispersion from substances that determine the properties of the soil;
• additives that regulate the viscosity of the primer (natural and synthetic resins, drying oil);
• drying process accelerators;
• fillers (dust particles of marble, chalk, mica);
• antiseptics;
• defoamers;
• tint pigments.

The impregnation of acrylic, depending on composition, is:

• deep penetration – can impregnate wood to a depth of 10 cm, strengthening it not only from the outside, but also from the inside. The primer works especially effectively on soft and old wood, chipboard and other loose materials. This result is achieved thanks to the addition of latex. It is he who is able to break through a dense layer of wood, firmly binding the fibers together. This primer increases the durability of the material, improves the quality of the finish, and reduces the consumption of paints and varnishes;
• adhesive – increases, with the help of fine-grained quartz sand, the level of adhesion to the base. Some manufacturers tint the compositions so that untreated areas are visible;
• impregnating – greatly reduces the ability of the material to absorb liquid substances. This is an ideal type of primer for wood for painting with acrylic paints;
• strengthening. The main task is gluing the pile of wood fibers without penetrating deep into. Designed for enamel painting;
• universal – combines the properties of the above compounds. It is not so effective when solving narrow problems, but in some cases only it can solve the problems that have arisen.

Pigmented solutions bring out the best features in wood’s structure and texture. particularly if the wood has been lightly sanded along its grain beforehand. There’s no need to finish in this instance. characterized by low cost, fast drying (1-4 hours), and lack of smell.

The need for multiple layers of priming and a negative response to low temperatures make it unsuitable for outdoor use, among other drawbacks.

Primer with alkyd. Alkyd varnish is the foundation of impregnation. It also says:

• fillers;
• agents-accelerators of the “drying” process (according to science – driers) – accelerate the polymerization processes;
• solvents, such as white spirit;
• stabilizers;
• coloring pigments;
• antiseptics.

The final mixture works better with liquid wallpaper, acrylic putty, PVA glue, alkyd and acrylic paints, and nitro paint. However, putties and plasters made of cement, sand, and gypsum are not advised. Alkyd primer for wood also strengthens the top layer, makes it more water resistant, keeps mold and mildew from growing, and uses less paint overall.

Let us observe a few additional salient features:

• withstands significant temperature changes – from -40 o C to +60 o C;
• saves paints and varnishes by 5-15%;
• increases wood resistance to abrasion and aggressive chemicals;
• reduces shrinkage when drying and swelling when absorbing moisture;
• closes pores for resin movement to the surface from resin pockets.

Strong smell; not recommended for interior work. However, its use makes sense in brand-new buildings where no one has moved in yet. In this situation, it’s crucial to give the house a thorough few days’ worth of ventilation.

Dries in a day or two. Internal use also requires consideration of this. It is advised to apply the alkyd composition in one or two layers to freshly cut wood that has never received any kind of treatment in order to achieve a smooth, lint-free surface.

The richness of the painted surface is enhanced by the robust matte film that pigmented primers create.

Important: paint must be applied to a completely dry surface.Certain paint types tend to curl up on wet primer.

It should be mentioned that the primer also has the excellent quality of matting previously painted surfaces.

In summary, compositions made to process street furniture, gazebos, and facades.

Silicone. Because acrylic dispersion is added to the water emulsion of silicone polymer, silicone-based primers are sometimes referred to as silicone-acrylic. The following is also included in the solution:

• antiseptics;
• fillers;
• defoamers;
• drying accelerators.

• durability – the longest service life among all wood primers;
• elasticity;
• low consumption – 100-250 g/m2;
• quick drying – about 3 hours is enough;
• ability to maintain properties in frost and heat.

The product’s price is impacted by these quality attributes, making it more costly than equivalents. used underneath water-based, silicone, and alkyd latex paints.

Sufficiently penetrates to create a hydrophobic layer. As a result, under the influence of temperature and humidity, the wood essentially does not deform and does not change its linear dimensions. The impregnated material is shielded from decay by the same characteristic. One disadvantage is that the material’s texture is not preserved.

The primary primer types that are taken into consideration. They are the ones that are, by far, most often, purchased. However, there are a number of additional kinds of primers and impregnations that serve particular purposes.

Shellac. Primers made of natural or synthetic shellac resins are primarily used to treat recently chopped coniferous tree wood. They block pores in the wood, preventing resin from rising to the surface. They remove pile, level the surface, and prevent knots from cracking all at once.

Used on deciduous trees to cut down on the amount of stain or water-based paint needed.

Epoxy. This kind of primer isn’t really meant for wooden structures. attaches them to parquet wood. This kind of impregnation prior to varnishing is perfect for it:

• protects from delamination;
• enhances adhesion;
• creates a hard layer on the surface of the parquet;
• shades the beauty of the natural material;
• protects wood from fading under ultraviolet rays.

Oil for drying. Drying oil was a traditional symbol of impregnations until recently. It became a primer after certain ingredients were added to its mixture, such as wax, siccatives, and antiseptics.

It is thoroughly absorbed, forming a barrier. One of the rare oil paint primers. Suitable for both internal and external tasks. However, in terms of processing facades, it falls far short of rivals.

Latex. Since it resists moisture better than all primers, it is used to prime wood in moist areas. Applyable to painted and untreated surfaces.

Polythene. utilized for impregnating flooring. On parquet, the functions are the same as those of "epoxy." They take about a day to dry out and smell powerful and prolonged.

By purpose

Primer types are categorized into three groups according to their intended use:

• antiseptics – protect wood from unfavorable biological factors;
• flame retardants – reduce the flammability class, reducing it to G1 (low flammability);
• primers – applied under finishing.

Functional features

Two methods are used by experts to categorize soil for wood based on its functional properties. Some individuals only perceive:

• adhesive solutions – penetrate deeply into the wood, creating good adhesion to the subsequent finishing material;
• leveling – create a good base for painting or varnishing.

Some split primers:

• on deep penetration primers – penetrate several centimeters deep into the material, protecting it from deformation and cracking, rot, fungus, mold, wood-boring insects, increasing the strength of the top layer of the treated surface. This type of primer has two disadvantages: it allows ultraviolet light to pass through and leaves pile on the surface, and therefore painting with enamel is not recommended;
• adhesive – regardless of the depth of penetration, they create good adhesion due to quartz sand with paintwork materials and plaster solutions;
• reinforcing – create a durable layer on the surface of the wood without penetration between the fibers. A prominent representative of the group is the epoxy primer;
• impregnating – create a powerful barrier against all types of liquid on the way inside the material, without penetrating too deeply.
• universal – have the properties of each of the above types, but not so accentuated.

Application area

Not every primer has an indoor and outdoor application. Some of the reasons could be that they smell strongly, take a long time to dry, are afraid of frost, or get washed out by rain. They are separated into primers for exterior and interior use based on this. Certain formulations have no limitations on their range of applications; they are universal.

By color

It is uncommon to categorize primers according to the color of their composition. but ineffective. Ultimately, this criterion determines the kind of treated surface. Therefore, colorless primer should be used on wood before varnish.

The beauty of the material’s structure and texture cannot be revealed in any other way. On a matte surface, the paint appears to have more saturated tones; in this instance, the primer is white. The process of tinting impregnation to mimic wood lets you skip finishing.

Which one to choose and in what case

No expert will suggest a particular kind of primer for every situation. The opposite will represent the pinnacle of impudence or unprofessionalism. However, the process of selection can be dissected.

You must first respond to a few inquiries. Few of them exist:

• will the tree structure be maintained?? If so, then the list includes colorless primers for varnishing and glazing (translucent) varnish and paint compositions (terraces, bathhouses);
• Is further finishing planned?? If the answer is positive, matte compounds are needed, if the answer is negative, tinted, but not always: they are also treated with colorless primers;
• what type of wood is processed? Here you need to take into account the density of the tree and whether it belongs to deciduous or coniferous species. For coniferous, previously untreated surfaces, shellac primers are optimal, and for dense ones (oak, hornbeam, ash, etc.) more fluid, for example, acrylic with the addition of latex;
• degree of processing? For rough surfaces, alkyd solutions are used, for polished surfaces – any;
• type of finishing? Alkyd compounds are used under enamel; it is better to paint over drying oil with oil paints, but when using water-based dispersions, you need to look at the compatibility of the primer and paint bases (can be found above in the text).

Furthermore, you should think about:

• work will be carried out on the outside or inside of the house. All types of acrylic primers are not used for exterior work – they are afraid of frost, but in warm regions of Russia nothing prevents priming a facade made of timber or rounded logs with this impregnation. Do not use compounds with a strong, most often chemical, odor inside an apartment or house;
• how long does it take to dry – if it is necessary to speed up the work, choose primers with a “drying” period of 1-4 hours;
• operating conditions – temperature and humidity influence. For a humid environment, compounds with latex are needed, but it is not necessary that it be the base.

We hope that the details offered will be sufficient for selecting the appropriate primer.

Popular manufacturers

Wood impregnations are produced by a few dozen companies. Consumers in Russia favor goods made locally (Aquatex, Senezh, and NEOMID companies) as well as goods imported from Finland (Tikkurila) and Slovenia (Belinka).

"Aquatex." The business is a member of the Rogneda group of businesses. specializes in producing bioprotective impregnation based on oil and wax.

Wood’s adhesive qualities can also be improved by changing the component composition. The types of fire retardants that are offered for sale do not contain fire retardants; further treatment against ignition will be required.

"NEOMID." Thanks to the introduction of 2 in 1 primers, which combine antiseptics and fire retardants, the company was able to dominate the market.

The solution is tinted for application convenience; processing gaps are readily apparent. Perfect for covering home, cottage, bath, and gazebo facades.

"Senezh." Senezh is a company that offers primers for various purposes, including pure primer, primer with bio-impregnation, fire-retardant mixture, and three-in-one solution, at reasonable prices.

There is a product that contains pigments that allow wood to be stained without the need for painting as a finishing touch.

"Belinka." Colorless bio-impregnations, penetrating acrylic primers for wood, wax impregnating compounds, azures for decoration, and coloring primers are among the products offered by the company.

"Tikkurila." The primary focus of the work is on paints and varnishes. However, there was also a location for wood impregnations, sometimes known as "Tikkuril wood."

It is of the same outstanding quality as paints. You can tint certain varieties yourself.

The most widely used primers for interior work are:

Interior of "Pinotex" With good reason, Estonian product leads the pack. Water-based primer functions well in all of Russia’s climate zones. Simple to use: applies evenly, dries quickly, and leaves no streaks. Once it dries, a final matte film is left behind that conceals surface imperfections while highlighting the material’s inherent beauty.

Among the benefits of becoming pregnant are:

• absence of components harmful to human health in the solution;
• a variety of colors to match different types of wood;
• high drying speed;
• no odor.

• high price – for 1 liter you will have to pay from 505 rubles.;
• most frequently counterfeited product.

"Tikkurila" Supi. A good substitute for Pinotex impregnation has been made by Finns; it works well in damp areas, dries to a semi-matte surface, and lets you add coloring pigments with the right color tone. It is typically used in baths and saunas. It effectively deters water.

• repels water and dirt;
• prevents the spread of microorganisms in the form of mold and mildew;
• economical consumption;
• versatility – you can process wood, fiberboard, chipboard and concrete surfaces;
• tinted at home.

Its cost is a drawback, albeit a significant one. You will need to pay from 7999 rubles for a 9-liter container. and upward.

"Aquatex" Supplement. At an affordable price, Aquatex products are a great choice. Works great as a primer, impregnation (prevents rotting, mold, mildew, blue staining, darkening, and fading), and decor for valuable woods.

• protects wood well from natural and biological unpleasant factors;
• preserves the pattern of freshly cut wood for many years;
• easy to use;
• affordable cost: manufacturers recommend retail prices to dealerships:

• 435₽ for 0.8 l;
• 1299₽ for 3l;
• 3699₽ for 9 liters colorless;
• 3830₽ for 10 l.

• takes a long time to dry;
• smells strongly of chemicals.

The top exterior wood primers are:

Aqua "NEOMID" BIO COLOR. The solution’s primary objective is to adorn wooden surfaces. In this instance, the surface that has been treated can either be painted using paint or left as a matte film to highlight the material’s structure and texture. Furthermore, biosecurity is optimal at this point.

Biocidal additives guard against UV fading, fungus and mold growth, insects, forest pests, and putrefactive processes. Wax prevents moisture absorption, which in turn prevents cracking.

Among the advantages

• affordable price – for a 0.9 liter bucket you need to pay from 323 rubles.;
• quality compliance with European standards;
• five-stage protection against biological and natural factors that negatively affect the material;
• designed for indoor and outdoor use;
• available for sale in almost all regions of Russia;
• large selection of colors;
• high drying speed;
• the ability to independently adjust the color by adding dyes.

Reviews from practitioners and forum users indicate that no flaws were discovered.

TL 30 STANDARD "Rhenocryl" The purpose of colorless bioprotective impregnation is primarily industrial production rather than custom building. The method used to process the wood is the cause. Just soaking. Not even a roller or brush. But only for external use. However, the public actively purchases it.

• German quality;
• dries quickly;
• without smell;
• absorbs well;
• does not change wood shades.

• is expensive – 711 rubles./l;
• not tinted;
• additional priming is required for painting.

Thus, this is an impregnation that is solely protective.

Dufa WOODTEX is a two-in-one alkyd impregnation solution. The antiseptic components of the solution perfectly shield wood from pests and diseases, while various oils, wax, and resin repel water, strengthen the wood, and give the wood a shiny appearance. Both indoor and outdoor use is possible.

• high quality;
• wide choice of colors;
• affordable price – for a 3 liter bucket you need to pay 1116 rubles.

No flaws were discovered.

Materials and tools

What you’ll need to impregnate wood products is:

• primer;
• cuvette for solution;
• roller or brush (large brush);
• brush – for treating small or difficult areas.

One sprayer can take the place of all of this.

Flow calculation

The same formula used to determine paint requirements is also used to determine the amount of primer needed:

• the processing area is determined;
• consumption per 1 m2 is multiplied by the area, and then by the number of layers;
• the result obtained is divided by the weight of the canister or bucket and rounded up.

In general, one layer is applied to hard wood species (oak, beech, white acacia, hornbeam, boxwood, etc.); on the remaining areas, two layers; and on chipboard and other porous materials, three layers. If we categorize it according to the method of impregnation, the consumption in the first layer is:

• for alkyd primer – 130 g/m2;
• acrylic – 120-150 g/m2;
• silicone – 200-250 g/m2;
• epoxy – about 100 g/m2;
• shellac-based solution – 200 g/m2 .

Choosing the appropriate wood primer is crucial for painting wood surfaces in order to achieve a smooth, long-lasting finish both inside and outside. Wood primers help shield the wood from moisture, mold, and mildew while also improving the paint’s adhesion. Understanding the differences between oil-based, water-based, and shellac primers—each appropriate for particular wood types and conditions—is essential to selecting the appropriate primer. You can guarantee long-lasting results and a polished appearance by choosing the right primer for your project.

Preparatory work

The wood needs to be ready before the primer is applied: If there was any previous finishing material, remove it and dust and clean it.

Crucial: Since the Soviet era, painting with paint over paint has been a common practice. Yes, you can do this in theory, but keep in mind that the new coating layer’s wear resistance will be significantly decreased. This is particularly important for wooden structures subjected to high mechanical stress, such as floors and street benches. As a result, it is preferable to prime the wood before painting after removing previous coats of paint or varnish.

Wood putty is used to fill in all the cracks and flaws. Sanding is done before varnish is applied.

How to properly prime wood

The technology of primers is straightforward. The ditch is filled with dirt. It is applied to ceilings, floors, and walls with a long-handled roller. A brush can be used for small products and difficult areas.

Having a spray gun makes the process even more efficient as it can be completed in a matter of minutes. Applying the paint in horizontal stripes from top to bottom is the same method as painting.

How long does it take for primer to dry?

The type of solvent and outside temperature affect drying times. Compositions containing water dry in roughly two hours. "Teknol" 1881 is an exception. Require a day.

Impregnations that are oil-based or that have just one kind of oil among their constituents can take 12 to 24 hours to dry. In this instance, the composition completely polymerizes over a longer time span in each succeeding layer.

The longevity and appearance of your finishes can be greatly affected by the wood primer you use for your projects. Primers are necessary to prep the wood surface, guarantee improved paint adhesion, and create a level, smooth foundation. Additionally, they aid in keeping the wood free from mold, mildew, and moisture—a crucial protection for outside work in particular.

Think about whether your project will be done indoors or outdoors when choosing a primer. Interior primers are typically designed with low odor and fast drying times in mind, which makes them appropriate for enclosed areas. Conversely, exterior primers are made to endure more challenging circumstances and offer increased defense against environmental factors and ultraviolet radiation.

There are three different kinds of wood primers on the market: shellac-based, water-based, and oil-based. Water-based primers are more environmentally friendly and easier to clean up after, but oil-based primers are more resilient and work well to seal stains. Although primers based on shellac are more adaptable and can cover a greater variety of stains, they can be more difficult to work with.

The primer you choose will ultimately rely on your unique requirements as well as the properties of the wood you’re working with. To make an informed choice, it is imperative to read product labels and comprehend their properties. Your wood surfaces will be well-prepared and protected if you take the time to select the correct primer, which will result in a stunning and long-lasting finish.

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