Recommendation points
About how to renew the varnish coating of wooden parquet, what materials and tools to use, we asked specialists with extensive experience in the restoration of parquet.
Parquet sanding
Parquet is sanded and re-varnished on average once every five years (the frequency depends on the intensity of use). You should not wait for the varnish to rub off to the wood, as the bare areas of the wood darken and begin to rot. Small defects can be sanded, putty and varnished, however, the repaired areas will differ in color from the old parquet – it is better to completely renew the varnish coating.
They remove the old varnish with professional tape, and finally process the surface with angular (for hard-to-reach places under the radiator, in the corners) and flat grinders – doing it manually is long and hard.
In addition to grinders, there are nail polish removers. The fundamental difference: the device is equipped with metal knives (cutters) that remove varnish with a top layer of wood. Therefore, after processing the surface with a router, grinding is still required. In addition, a professional milling cutter (for example, METABO) is quite expensive (about 500 euros).
On sale there are household belt (price 2000-3500 rubles) and flat (from 500 rubles) grinders, but in terms of quality and processing speed, these tools are inferior to professional.
You have a choice: to restore the parquet yourself (professional equipment can be rented for approximately 20-60 USD per day, plus a deposit equal to the cost of the car – 200-300 USD) or entrust the work to the parquet masters (it is worth updating the varnish coverage on average 180 rubles per square meter). In either case, all consumables (sandpaper, putty, varnish) are purchased separately.
It is better to remove the skirting boards before sanding so that the grinder can come close to the walls and remove the old varnish without residue.
Parquet putty
After sanding, scratches and chips are sealed with a special putty to match the color of the wood and the repaired areas of the floor are cleaned with sandpaper. The varnish is applied after the final drying of the putty (1-5 hours).
Specialized putties for wood (putties) are made water-based (acrylic) or based on nitro-solvents. Water-based putties (for example, “Pinocolor”, “Belinka”) have practically no smell, dry quickly, but are inferior to the second type of putties in strength (though they cost 2-3 times cheaper, say, “Pinocolor” – 30 —40 rubles / 150 ml, and Plastic Wood (USA) – 80 rubles for 118 g). The putty is applied in a very thin layer (no more than 1 mm); if necessary, you can apply another one, but only after the first one is completely dry.
Water-based putties and varnishes are not recommended for certain hardwoods (oak, chestnut, cedar, etc.), as bluish-whitish spots may appear on the lacquer coating.
An alternative to putties is special waxes for parquet restoration: they do not shrink, are translucent, but they are much more expensive (about 124 rubles / 30 g). In addition, polyurethane varnishes cannot be combined with waxes, otherwise the varnish coating will peel off..
The parquet is covered with special water-based (acrylic) or artificial solvent-based (polyurethane, alkyd) varnishes of increased wear resistance. As a rule, water-based varnishes (for example, “Tex”) dry faster, have no odor, do not change the color of the wood and are diluted with plain water; however, their price is also higher (on average by 50 rubles / l).
Types of parquet varnishes
Water-borne varnishes
According to experts, in recent years, parquet varnishes based on aqueous dispersions of acrylic and acrylurethane polymers have become widely used on the market. These varnishes do not contain organic solvents and at the same time in their properties not only are not inferior to solvent-borne varnishes, but also surpass many of them in terms of wear resistance of coatings and resistance to detergents.
Odorless and free from organic solvents, water-based varnishes can be used in hospitals, child care and other crowded areas.
Considering the specificity of water-based materials, when varnishing floors with an existing coating, special attention should be paid to surface preparation. In this case, the floor must be thoroughly cleaned of dirt, grease and wax and sanded to a matte finish. Sanding dust should be removed with a vacuum cleaner and the floor should be wiped with a damp, lint-free cloth.
If the old coating is badly worn out, then the floor is sanded to clean wood, and then all operations are carried out by analogy with finishing the new parquet.
Due to the fact that the application of water-based varnishes to wood may be accompanied by the raising of the pile, it is advisable to slightly moisten the wood after sanding and sand it again after drying. A water-borne primer is applied to the parquet floor surface prepared in this way. The primer, in comparison with the varnish, has a higher dry residue and viscosity, therefore, when applied to the floor, it fills microcracks in the parquet well and glues the pile.
The primer is poured onto the floor and spread evenly over the entire surface with a wide steel trowel. This should be done quickly so that the primer is evenly absorbed into the wood..
The primer layer dries very quickly (30-60 min), which speeds up the entire varnishing process. In addition, the new generation of acrylurethane-based primers prevent darkening of oak parquet, while water-borne varnishes (especially the “old” range), when interacting with tanning extracts, give the floor an unpleasant dark shade.
After the first layer has dried, the primer is sanded with a fine sandpaper, and then another 1-2 layers are applied with a metal spatula with an interval of 20-40 minutes.
After the last coat of primer has dried, you can start applying the varnish. Before use, the varnish is thoroughly mixed (especially if it contains a matting additive) and allowed to stand for about 10 minutes to remove air bubbles. If necessary, the varnish can be thinned with drinking water, but not more than 5%.
The varnish is applied with a wide brush with thick soft hair or a paint roller in the direction of the wood grain or light from the window, without pressing hard on the tool. The roller should be rinsed with water before use to remove dust and lint. When applying the varnish, avoid visible joints and roundings..
The varnish coating dries up in 2 hours. However, it is recommended to subject the varnished floors to stress after 3–5 days of exposure at a temperature of + 15–25 ° С. Complete drying of the varnish occurs in 1-2 weeks.
Low temperature and high humidity will slow down drying of the coating and lengthen the holding time. To obtain a high-quality coating, varnishing is carried out in 2-3 layers.
Organo-thinned varnishes
Among the traditional varnishes for finishing parquet and wooden floors can be named:
– alkyd
– alkyd-urethane
– epoxy
– alkyd-carbamide varnishes
Alkyd varnishes are cheap, easy to repair, and the solvents they contain are not very toxic. However, alkyd varnishes take a long time to dry (about 48 hours), coatings based on them do not have very high wear resistance.
An alternative to alkyd varnishes are alkyd-urethane varnishes (uralkides), which are solutions of alkyd resins with urethane groups in organic solvents. Uralkyd varnishes dry faster than alkyd varnishes (the holding time before applying the next layer of varnish is 6-12 hours) and have a significantly higher wear resistance.
Acid curing varnishes
The composition of acid-curing varnishes (also called catalytic varnishes) includes: a mixture of alkyd and amino-formaldehyde resins, solvents and various additives to improve flow. Two-pack acid-curing varnishes: the second pack is an acid hardener (solution of strong organic or inorganic acids in an organic solvent).
The working composition – a mixture of varnish and hardener (usually their ratio is 10/1) – is prepared immediately before application. The mixture should be thoroughly mixed and left for 15-20 minutes to remove air bubbles.
Ideal conditions for varnishing: air humidity – no more than 50%, wood moisture – no more than 10%, room temperature – above + 18 ° С.
When working, new sanded surfaces should be treated 2 times with nitro varnish with intermediate sanding, and then apply 2-3 layers of varnish with a brush, a wide metal or felt trowel.
The drying time of the coating is 1–2 hours, the curing of the multilayer coating lasts 1–2 days, during which it is not recommended to stay indoors, since it is at this time that the maximum evaporation of solvents and the release of formaldehyde from the coating are observed. Curing is accelerated with good air exchange in the room. Full cure occurs in about two weeks, when the coating acquires maximum wear resistance.
Parquet varnishing
The varnish is applied in at least three layers. The more layers, the stronger the coating. After each layer has dried (except for the final one), for better adhesion, subsequent ones are manually smoothed out irregularities.
First, a brush goes through all hard-to-reach places, near the walls, in the corners, and then varnish is applied to the surface with a velor roller, preferably along the wood fibers.
It should be borne in mind that when painting the parquet with acid-cured varnishes, it is necessary to ensure good ventilation of the air in the room, as well as, if possible, use respiratory protection.
Attention: when using varnish, it is forbidden to smoke and use open fire. It is strictly forbidden to pour the varnish into the sewer!
