Technical characteristics and application technique of alkyd-urethane varnishes

Alkyd-urethane varnish is a mixture of alkyd resins and urethane components, diluted with an organic solvent. Such a varnish is used for processing any wooden surfaces, including parquet, furniture, stairs, yachts, etc. Alkyd-urethane compounds are used for varnishing, both fresh wood and one that has already been varnished.

Content:

• Advantages
• Technical standards
• Preparatory Activities
• Application
• Painted surface care
• Precautionary measures
• Alkyd-urethane varnish “yacht”

Note! Mixtures of the alkyd-urethane group are not intended for surface treatment in saunas, baths and other rooms exposed to excessive moisture.

Advantages

Alkyd-urethane mixtures differ in a number of positive characteristics:

1. Attractive appearance.
2. Fast drying (the average waiting time is shorter than in the case of alkyd varnishes, and subject to technological procedures does not exceed 6-12 hours).
3. High wear resistance and increased hardness of the coating (according to this indicator, an alkyd-urethane group is also preferable to alkyd compositions).
4. The mixture is easy to apply and evenly distributed over the surface, after which the wood becomes dull or semi-matt.
5. Resistance to humidity and household chemicals.
6. Protecting the floor from contamination.
7. Almost complete absence of odor (the mixture is based on slightly aromatic solvents).
8. High elasticity of the coating, so that the material is not susceptible to cracking when resizing a wooden product.
9. Bonding of the ends of the parquet does not occur. Thus, it is possible to avoid stress of the material.
10. No priming of the surface is required before applying the varnish on the previously varnished surface.
11. Parquet treated with an alkyd-urethane mixture is not slippery when walking on it.
12. Varnishes of this group allow you to intensify the natural color of the tree, making the surface pattern more accentuated.

Technical standards

Below are the main parameters that the varnishes of the alkyd-urethane group should correspond to:

1. The maximum possible content of volatile organic compounds is 500 grams per liter.
2. According to ISO 2813, the gloss of an alkyd-urethane mixture should be matte or semi-gloss.
3. Qualitative parameters of varnishes of this group are prescribed in the ISO 9001 standard.
4. The maximum permissible wood moisture content is 18%.
5. The optimum temperature for applying the composition is from 10 to 25 degrees above zero, and humidity can range from 40 to 75%.
6. The recommended temperature of the varnish at the time of applying it to the surface is from 18 to 25 degrees Celsius.
7. The consumption of paint and varnish material is 1 liter per 8-12 square meters of coverage.
8. Drying time from dust is 2 hours. The final drying takes place in a day, provided that the humidity is approximately 50%, and the air temperature is in the region of 23 degrees above zero.
9. Guaranteed shelf life is 5 years.

Preparatory Activities

Surface preparation is subject to the following rules:

1. It is unacceptable to varnish the surface in direct sunlight, as well as in drafts.
2. Before processing, remove dirt, grease and oil stains from the surface.
3. If the wood is a hardwood, soak it with a white spirit solvent.
4. Rough places are treated with spray water. When the surface dries, we grind it to remove the raised wood fibers.
5. If the surface has previously been varnished, we check the paintwork materials for compatibility. To do this, do a test stain in a small area. Please note: the final color of the coating depends on both the type of wood and the number of layers of paint applied.
6. Varnished surfaces may not be primed, but if the varnish is peeling off, it must be removed and then the surface sanded twice. Please note: for the first time we grind wood with a clear effort using rough sandpaper. The second time we grind more carefully using fine-grained sandpaper.
7. If the varnish will be applied to fresh wood, it should be primed with White Spirit. Recommended proportion: for five parts of the solvent, one part of the paint composition.
8. After polishing the surface, remove the dust with a vacuum cleaner. Moreover, the dust should be removed not only from the floor, but also from all nearby areas: the heating battery, baseboards, window sills, etc. It is impossible to prevent a situation where chips or dust fall on a floor that is not dry from varnish.
9. Wipe the wood with a clean, slightly damp, lint-free cloth.

Note! Although alkyd-urethane varnishes are more often used for application to wood, they can also be used for concrete.

Application

Stir varnish well before use. And we do it in such a way as to avoid bubbling. If the varnish is not mixed, it will not be possible to achieve a uniform tonality of the coating.

We apply the alkyd-urethane mixture in two or three layers, since this composition is very deeply absorbed into the wood structure. If the tree is not too porous, you can limit yourself to a couple of layers, however, for highly porous rocks, three layers are needed. Lacquer layers should be thin, so drying the surface will be faster. Varnish the surface in the direction of wood fibers or from the side of the window. Before applying each subsequent layer, we expect complete drying of the surface.

Advice! The surface will dry much faster if the room has good air circulation.

If necessary, tinting wood is recommended to carefully read the instructions from the manufacturer. For example, when applying “Aura Balance” varnish, the color composition is applied first, and the colorless coating composition is used for the remaining layers.

The varnish is applied to the surface with a brush, roller or a special spatula. The bristles should be held firmly on the tool to avoid getting it on a dry coating. It is recommended to use a varnish spatula in cases where a light tone of the coating is required. The fact is that when working with a spatula, the paint material is absorbed into the wood less significantly than in the case of a roller or brush.

If the floor will be operated under high loads, it is recommended to give preference to hardwood parquet. The fact is that soft varieties (pine, spruce, etc.) will be deformed regardless of the strength characteristics of the varnish.

Advice! If varnishing of wood is done in a dry and hot climate, it is necessary to limit excessive air circulation. This is necessary to prevent the floor from drying out too quickly, resulting in cracking of the coating.

Painted surface care

Coatings for the decoration of which alkyd-urethane varnishes were used achieve maximum strength 3-4 weeks after application of the composition.Prior to this, they are vulnerable to external factors. Therefore, recently lacquered surfaces should not be cleaned with household cleaning products. If during the first month there is a need to clean the coating, it is recommended to use a soft damp cloth for this.

Precautionary measures

Storage and transportation of alkyd-urethane compounds should be carried out at a temperature not exceeding 30 degrees above zero. Varnish must be protected from direct sunlight.

When storing, transporting and using varnish, safety precautions should be observed, since alkyd-urethane formulations contain butanone oxime and cobalt bis. In humans, these substances can lead to an allergic reaction, manifested in dryness and cracking of the skin.

Important! Alkyd-urethane mixtures cannot be disposed of in the sewer system. It is also unacceptable for varnish to enter an unprotected environment.

Alkyd-urethane varnish “yacht”

Special varnishes are available for varnishing yachts.characterized by increased resistance to external factors. On the basis of alkyd and urethane, two types of paints and varnishes are produced - alkyd-urethane and urethane-alkyd. These mixtures differ in the concentration of the basic substance: in alkyd-urethane, there are more alkides and, conversely, in urethane-alkyd varnishes, urethane prevails.

This type of varnish provides a high-quality, hard, resistant to low temperatures and precipitation. However, the main feature of alkyd-based paint and varnish mixtures is the highest drying rate of the varnished surface. Manufacturers achieve this characteristic by adding particularly volatile solvents to their formulations. Such substances evaporate very quickly - much faster than ordinary white spirit. However, the use of rapidly evaporating solvents results in a very high toxicity of the varnish.

Urethane-alkyd paints are designed specifically for indoor use. Unlike alkyd-urethane, the concentration of organic solvents is lower in urethane-alkyd varnishes. Also important is the fact that urethane-based plasticizers are inhibitors that prevent the evaporation of chemicals. Due to the urethane component, the coating acquires elasticity and increased resistance to temperature extremes.

Urethane-alkyd varnishes are recommended, first of all, for application to the so-called "warm floors". Most other varnishes under conditions of regular heating simply crack. And only wood coated with a composition where urethane predominates is guaranteed to retain its performance characteristics.

Alkyd-urethane varnish is one of the best solutions for varnishing a wooden surface, distinguished by its undeniable advantages. However, the alkyd-urethane coating, like any other, wears out over time. Therefore, after 7-10 years, coverage updates will be required. It is also necessary to remember the toxicity of alkyd-urethane mixtures and to take timely precautions when handling this paint material.