Wood has optimal conditions for long life indoors. Humidity, which is the main reason for using protective coatings, is low inside, wood is removed from the sun, fungi and insects do not have access. Indoor wood has very low needs for chemical protection and expectations of indoor wood coatings are different from those for outdoor wood.
Due to the favorable living conditions, we have a very wide range of coatings available. With many pieces of furniture, the coating can be avoided, but because it also makes it look better, most wooden products have some kind of protection. The coating for wood indoors must protect against impurities, it must be resistant to mild cleaners and occasional spills. When we come across quality wood, translucent stains, oils and waxes are used for interior coating. With them, the wood gets basic protection, while preserving and even emphasizing the structure of the wood. Thick-layer decorative coatings are used mainly on wood of lower quality, where visible years are not in our interest, or in the restoration of old furniture, where we want to recreate the appearance of old oil paints with a thick coating.
It is recommended to use products that maintain a healthy living environment in living spaces. Coatings intended for outdoor use do not belong to the interior or should, according to European guidelines, be physically sealed with a good topcoat or similar.
1. Preparation of wooden surface
Good surface preparation is one of the factors that provide the desired
quality of processing.
Basic processing factors include grinding, smoothing and
dedusting. There is a well-known saying among experts: “Well sanded – half varnished”.
Staining is a technological process that changes the natural color of wood without overlaying
its texture. We can emphasize the texture or partially blur it. By leaching you can
we enliven the natural color of wood, imitate the color of noble tree species or the wood surface
we grow old.
3. Primary color
According to the composition, there are various coatings that allow decorative painting of the surface.
They differ from stains in terms of color effects, and they are also slightly easier to process.
Primer paints are divided according to composition and purpose of use into several groups:
1. Nitro primer
2. Polyester primers
3. Polyurethane primers
4. Oil base paints
5. Water-based primers
4. Coating agents for wooden surfaces
Coating or coating agent is a general term for a substance that is applied in a thin layer to
the surface of the wood and after the hardening process forms a thin hardened film on the surface. Properties of hardened
varnish film depends on the properties of the basic components of the coating.
– COATINGS BASED ON NATURAL MATERIALS
5. Types of varnishes
1. Nitrocellulose varnishes
In terms of quality, they can be classified as coatings based on natural
resins and coatings based on synthetic binders.
2. Polyurethane varnishes
Unfortunately, many polyurethane varnishes are prone to yellowing under the influence of UV light.
The consumption of polyurethane varnishes is growing, especially for the production of quality furniture, restrictive
the factor is their relatively high price.
3. Polyester varnishes
Polyester varnishes are a classic tested group of varnishes in many different compositions
used for a variety of wood treatments. However, it is an ecological objection (styrene has a very low permissible concentration).
4. Polycondensation varnishes with acid hardener
These varnishes are known as “acid varnishes”. Consumption of these varnishes is declining and will continue to decline for ecological reasons.
5. Water-based varnishes
They are a group of water-based varnishes that use a wide variety of binders.
They have a lower content of organic solvents or even without them and are dispersed in water.
The most commonly used acrylic, polyurethane, unsaturated polyester, acrylic-styrene
copolymer, acrylic-polyurethane copolymer binders.
6. Acrylic varnishes
Acrylic varnishes represent a newer, less tested group of varnishes in wood surface treatment.
The main ingredient in these varnishes is acrylic resin, which can be composed very differently.
6. Coatings based on natural materials
1. Natural oils
These are oils of vegetable or animal origin that contain more or less unsaturated double
bonds between carbon atoms. Depending on the number of double bonds, the oils are drying, semi-drying
Drying oils include flaxseed, tung, dehydrogenated castor, hemp oil and
various fish oils. The most common semi-drying oils that we also use are soy and
sunflower oil. Flaxseed oil is mostly used, but it hardens for a very long time (even more than one
week). For practical use, therefore, linen varnish containing thermal is more commonly used
treated flaxseed oil to which hardening accelerators are added.
2. Natural resins
Rosin, Mastic, Shellac.
They are naturally or synthetically derived substances that are esters of higher fatty acids and saturated alcohols. Furniture is surface treated with waxes for three reasons:
– to protect surfaces from external negative influences,
– to emphasize the beauty of wood,
– to maintain a healthy living environment.
Waxes do not dissolve in water, they dissolve in organic solvents, turpentine, gasoline, benzene and other stronger organic solvents, as well as in warm alcohol. Waxes can be vegetable,
animal, synthetic and mineral.