Purpose and types of finishing of wood and wood materials. Processing of wooden products. Methods for finishing finished wood products List of works for finishing wood products
Depending on the type of wood from which the product is made, its purpose and the requirements placed on it, finishing is carried out in various ways. Finish can be
- - transparent,
- - opaque (opaque),
- - imitation (carving, inlay, modeling, etc.).
Transparent, or carpentry, finishing is used in the manufacture of wood products valuable species or veneered products. Its main purpose is to create on the surface of wood a durable transparent colored or colorless, smooth, shiny or matte protective and decorative film that maximally reveals or improves the natural decorative qualities valuable wood species.
Opaque, or opaque, finishing creates a durable opaque colored smooth shiny or matte protective and decorative layer on the surface, hiding the natural texture of the wood. Opaque finishing is used for products made from wood of low-value species that do not have beautiful texture, for items used outdoors, as well as products special purpose(kitchen, hospital furniture, etc.).
Imitation finishing is used in the manufacture of products from low-value coniferous and hardwood; its goal is to create a new texture on the surface or color the wood fibers to match the color of valuable species. Protective and decorative film can be opaque or transparent.
Finishing largely determines appearance products and consumer choice, and finishing materials are designed to provide the product not only with attractiveness, but also with protection from exposure various kinds factors?? - mechanical damage, changes in temperature and humidity, etc. All protective and decorative coatings (PDC) can be divided into three groups: solid facing and finishing, liquid paint and varnish and powder. Industrial enterprises also produce combined paintwork materials, which include paint and varnish materials (paint and varnish materials) along with facing materials.
The group of solid facing and finishing materials includes planed or peeled veneer, plastics, polymer and paper-resin films. Natural or synthetic film formers can be used as the basis for liquid paints and varnishes. Materials of each group can be organosoluble and water-soluble. Water-borne products are divided into water-soluble and water-dispersible.
Paints and varnishes are multicomponent systems. The main part of all paints and varnishes are natural or synthetic film formers, that is, substances that, after being applied to the surface of wood in a thin layer, are capable of forming, under certain conditions, a thin and durable film that provides good adhesion to the surface of the part or product. Components of finishing materials also include film-forming solvents, plasticizers, coloring agents, fillers and, in some cases, substances that are necessary to accelerate curing processes.
Paints and varnishes are classified according to chemical and operational characteristics, coating structure, optical properties and state of aggregation. The basis chemical classification depends on the nature of the film-forming substance from which the coating is made. In this publication, we will not talk about the basics of forming a fire protection zone for wood and wood materials and consider their structure and structure, we are interested in the application in practice of enterprises of one or another type of coating materials used in finishing technologies.
Based on their operational characteristics or purpose, coatings are divided into weather-resistant, chemical-resistant, heat-, frost-, water-resistant, etc. Based on their structure, paintwork is divided into single- and multi-layer. For multilayer coatings, the following names of layers are accepted: the first (in contact with the substrate) is primer, or primer, the next layers are intermediate, and the top one is cover.
Based on their optical or decorative properties, coatings are divided into transparent and opaque. Transparent ones are most often used for processing wood and wood materials with beautiful texture and color. To form transparent coatings Colorless nitrocellulose, polyester, polyurethane varnishes or films are used.
Opaque coatings completely hide the color and texture of wood and wood materials. This type of ZDP is used for processing coniferous or low-value deciduous wood. They are also used for products that have increased performance requirements (for example, kitchen furniture). To apply opaque coatings, opaque materials are used, which include paints, enamels, powders and films based on impregnated papers.
Depending on the appearance indicators, paintwork is divided into two subgroups: open-pore (A) and closed pores(B). Distinguish paint coatings Based on the degree of gloss or dullness, a simple classification allows: high-gloss (HG), glossy (G), semi-gloss (PG), semi-matte (PM) and matte (M).
For paint and varnish coatings, two categories are established: in the first, surface defects are not allowed, in the second, individual surface defects in the form of single strokes, scratches, punctures, bubbles, etc. are possible.
Depending on the type of main film-forming agent, paint and varnish coatings are divided into seven groups: polyester (PE), polyurethane (UR), melamine (ML), polyacrylic (AK), urea (UC), nitrocellulose (NC), pentaphthalic (PF).
Depending on the state of aggregation of paintwork materials, protective and decorative coatings can be formed on the basis of liquid paintwork materials, powders or film materials. Manufacturers of paints and varnishes today produce in increasing volumes water-based and powder materials, as well as compositions that do not contain volatile components and are applied in the form of melts - the so-called 100% varnishes and paints. IN furniture production the share of use of water-dispersed coatings has increased significantly. It's environmentally friendly clean materials ensuring production safety. The cost of such materials is low, and the coatings have physical, mechanical and operational properties that are not inferior to organic-soluble products.
Liquid varnishes are solutions of film formers in organic solvents or water. The range of produced varnishes for wood finishing is very diverse. In furniture production, nitrocellulose (nitrovarnishes), polyester, polyurethane, alkyd-urea, and acrylic varnishes are mainly used.
Nitrovarnishes are characterized by a low content of non-volatile substances (24...33?%). Nitro varnishes have quite a lot of advantages. These products are convenient and easy to use. They dry quickly and form coatings with high decorative and physical and mechanical characteristics. Varnishes are intended for finishing furniture and other products used indoors. Domestic companies producing paints and varnishes have developed nitro-varnishes containing a matting additive, used to obtain matte coatings, and nitro-varnishes intended for imitation finishing of chipboards and wood-fiber boards.
The advantages of polyurethane varnishes are low consumption, no need for grinding and polishing the treated surface to obtain a high-quality finish. Such coatings are characterized by a high degree of gloss, abrasion, weather, water and moisture resistance. Two-component alkyd-urea varnishes are successfully used to provide a high-quality thin-layer transparent matte finish of panel parts of furniture with open pores and products of lattice structure. These inexpensive varnishes are also low in consumption. After applying alkyd-urea varnishes, the surface does not need to be refined - this is another plus that allows for a high economic effect of production.
Acrylic varnishes are ideal for finishing kitchen furniture, especially light colors, on the surface of which the change in color shade over time becomes quite noticeable. These varnishes are characterized by high physical and chemical resistance to scratches, exposure to water, coffee, alcohol and almost do not turn yellow over time.
Polyester varnishes
On the Russian market, polyester varnishes of Russian or foreign production can be purchased from the companies Technocolor, Lac-Premier, LIGA, TimberAL, BaltPromKomplekt, Industrial Paints, Trading House EuroChem-1, I.T.I.", "ART-Industry", "Phaeton", Tanzor-M, "TENDENT", "LKM ServicePlus", "Somek", "Trade and industrial company "INFRAHIM"", "Production association ""Paints for Everyone"", "Fibrolite", "CHELAK", FKP "Kamensky Plant", "VitaChem". The advantages of polyester varnishes: large dry residue, excellent filling ability, high hardness and physical and chemical resistance. When dry, such varnishes form a hard film of great thickness, resistant to various reagents and water. Polyester varnishes are usually applied to the surface of products by pneumatic spraying or pouring (using a varnish-filling machine).
Polyester varnishes are divided into paraffin-containing and non-paraffin (hot or cold curing). Paraffin-containing varnishes are characterized by a high content of film-forming agents (93-97?%), which determines their high efficiency. Such varnishes are used to obtain coatings with a mirror shine or matte coatings for the front and facade surfaces of expensive furniture. Paraffin-containing varnishes can be applied in thick layers, since their shrinkage is small, and curing occurs faster and more reliably in thick layers than in thin layers, so a coating with a thickness of 300-400 microns can be obtained in one or two applications. Priming and filling the substrate are rarely used when finishing with paraffin-containing varnishes.
The main disadvantage of varnishes containing paraffin is their low adhesion to wood. These varnishes are characterized by low viscosity and high fluidity. Solutions of these varnishes have a short pot life (about 30 minutes). Because of high turnover paraffin-containing varnishes are used mainly for finishing horizontal panel surfaces. When applied to vertical surfaces, special additives are introduced into them.
If, when preparing the wood surface for finishing, painting is not intended aqueous solutions dyes, it is allowed to treat rough surfaces with such varnishes, since the varnish does not cause noticeable swelling of the surface layer of wood. For the same reason, from technological process the operation of removing wood lint can be eliminated.
Paraffin-free varnishes contain about 70?% film formers. The pot life of working solutions of these varnishes is at least 20 hours. Coatings based on paraffin-free varnishes, in contrast to coatings based on paraffin-containing varnishes, are characterized by higher elasticity and adhesion to various substrates. Wax-free polyester varnishes are easy to use. They are often used in combination with polyester primer plus polyurethane varnish or enamel."
Domestic manufacturers of paints and varnishes produce many brands of polyester varnishes. For example, varnishes of the PE-246, PE-265, PE-2136 brands are suitable for forming high-gloss coatings on panel furniture parts lined with natural, synthetic veneer or materials based on impregnated papers. They also produce PE-2136U ultraviolet-curing varnish, which ensures the formation of high-gloss coatings on panel furniture parts lined with natural, synthetic veneer or materials based on impregnated papers. Varnish PE-2311 is intended for obtaining matte coatings with a finished effect on panel furniture parts lined with natural veneer or materials based on impregnated papers, and varnish PE-2315 is intended for obtaining glossy coatings of a similar effect. For finishing wood products used indoors, followed by polishing, as well as for painting musical instruments High-gloss varnish of the PE-232 brand is in demand. Varnish PE-251 is intended for obtaining transparent glossy coatings. It is mainly used for high-quality finishing of chairs, armchairs and other products from solid wood. Manufacturers produce grades PE-251A and PE-251 B.
If desired, the craftsman can improve the appearance of his product and protect the wood structure from the harmful effects of precipitation. It is not always possible to purchase veneer or valuable wood. The ideal solution This problem is solved by the use of various tinted varnishes, with which you can obtain a walnut, mahogany, etc. finish. For the same purpose, stains and stains are used. Beitz is a dry dye powder, and stain is a ready-to-use aqueous or alcohol solution of the required concentration. Synthetic dyes are also commercially available.
In the event that the craftsman is not satisfied with the dyes produced industrially, there are numerous recipes for staining and dyeing wood, according to which you can independently make the necessary composition.
Finishing the surface being treated is understood as creating a protective and decorative coating on it in order to improve the appearance and protect it from exposure environment. To create a coating, use various materials: paint, film, plastic, etc.
Finishing materials must have good adhesion, that is, reliably adhere to the wood. The most common among them are paints and varnishes, applied to the surface of wood in several layers.
In order to reduce the consumption of finishing materials during multi-layer processing, pore-filling compounds are used before painting: primers, putties, etc. Thanks to pre-treatment with these materials, which are also cheaper, the surface is leveled, which promotes better adhesion to enamels and paints.
Depending on the nature of the materials used and their decorative properties finishing can be transparent, opaque, imitation and special. With a transparent finish, the texture of the wood material is preserved. The opaque coating completely hides the natural color and grain of the wood. Imitation finishing reproduces a certain color and pattern on the treated surface. Special includes various decorative elements.
Transparent coatings are used mainly in cases where the wood from which the furniture is made has a beautiful texture. Such products are recommended for use in interior decoration of residential premises.
A transparent coating on the surface being treated is created using liquid or film materials. This finishing is carried out on hard and valuable deciduous wood. The simplest type of clear coat is a thin layer of varnish.
Opaque finishing is applied to products made from low-value species whose wood texture does not have a beautiful pattern. This type of finishing is used in cases where it is necessary to give the surface high stability to influence external factors. This coating is performed with pigmented enamels, which are applied in several layers. Before applying a layer decorative paint Initially, deep unevenness is removed from the treated surface. For this purpose, it is puttied and cleaned.
Imitation finishing improves the decorative qualities of wood. It consists of applying to the surface sheet materials and knots that imitate the texture of valuable wood species. The surface of products made from low-value species is coated with special dyes, pasted over with textured paper, films, and decorative plastic.
Special finishing is the decoration of furniture: metallization, gilding, creation various decors(typesetting, ornamental, relief), overlays and inserts.
Special types decorative finishing are various ways burning, carving, relief inserts and overlays, mosaics, etc. The material, shape and artistic processing are very diverse, but in any case they must correspond to the style of the given product or set of furniture.
In order to finish the surface of the wood, several sequential operations are performed. First, the wood is prepared for finishing, then it is painted, primed, filled with all pores and covered with a layer of varnish.
From the book: Korshever N. G. Works on wood and glass
§ 36. Types of wood finishing.
All types of finishes can be divided into the following main groups: transparent, opaque, imitation and special.
With a transparent finish, the surface of the wood is covered with colorless finishing materials, preserving or even more revealing the wood texture. It is used for finishing furniture and high-quality construction products: windows, doors, panels made of valuable wood.
Transparent finishes are obtained by varnishing, polishing, waxing and coating with transparent films. When finishing by varnishing, varnishes are used that contain film-forming substances in organic solvents, solvents, etc.
Most often, polyester nitrocellulose and urea-formaldehyde varnishes are used for finishing wood, and less often - oil and alcohol varnishes.
Nitrocellulose varnishes dry well, produce a strong, elastic, transparent and fairly weather-resistant film that can be sanded well. Varnishes based on urea-formaldehyde resins form a film with a shiny surface that is quite transparent. The film formed by oil varnishes is elastic, durable, weather-resistant, but not decorative enough; alcohol varnishes produce a film with insufficient strength, weather resistance, and low gloss.
First class coatings must be smooth and smooth surface without visible defects. For transparent coatings of this class, dyeing defects, whitening of fillers in the pores, etc. should not be visible.
Second class coatings must be smooth, plain or with characteristic patterns.
Some subtle defects (strokes, marks) are allowed. Third class coatings must be smooth and even. Individual noticeable fluff, traces of cleaning, and unevenness resulting from machining
wood before finishing. With a transparent finish there should be no drips, waviness or scratches.
Class 4 clear coats (semi-gloss) should be smooth to the touch and slightly shiny. For coatings of this class, defects are allowed that are visible to the eye, but do not affect the condition of the coating itself. A type of transparent finish is polishing. The main material used is an alcohol polish, which is a solution of shellac resin in ethyl alcohol
. The polish is applied repeatedly in a thin layer to the surface of the wood. When waxing, i.e. applying a mixture of wax with volatile solvents (white spirit, turpentine) to the surface of wood, it also turns out transparencies
, formed by a thin layer of wax (volatile solvents evaporate during the drying process). The wax coating is usually applied to porous wood (oak, ash). The wax film is soft, so it is covered with an additional layer of alcohol varnish. The wax coating has a matte surface. At
opaque finishing creates a film on the surface that covers the color and texture of the wood. Opaque finishes are used in the manufacture of school, kitchen, medical, built-in and children's furniture, doors, and windows. For getting opaque coating use oil, nitrocellulose, alkyd, perchlorovinyl,
water-based paints and enamels. When painting with enamels with a large content of film-forming substances, glossy coatings are obtained, with a smaller amount - semi-gloss, and when painting
oil paints consists of applying a finishing layer of molten and powdered metal (metallization), molten resins and other materials to the surface of wood, as well as performing various decorative works on wood (carving, inlay, burning).
Performance paint and varnish coatings must have a number of physical and mechanical properties: adhesion to wood, hardness, heat, light and water resistance. These properties are of significant importance in the operating conditions of the products. They are determined by the quality of paints and varnishes, the conditions of their application, and drying of coatings.
Adhesion refers to the strength of adhesion of the paint coating to wood surface, and this factor depends on the composition of the paint and varnish materials, the thickness of the paint layer, etc. Homogeneous compositions - nitrovarnish and nitroprimer, oil primer and oil varnish - have higher adhesion. Heterogeneous compositions have weak adhesion: wax and oil, oil paint and adhesive primer, as a rule, peel off quickly. This should be taken into account when selecting paint coating compositions.
Hardness is understood as the resistance of a paint coating to the penetration of a harder (non-deformable) body into it, i.e. the ability of the coating to resist the influence of a foreign object.
Water resistance is the ability of a coating to withstand the effects of water on the surface of a product. It plays a very significant role in the operation of carpentry products (window blocks, external doors) in conditions of variable humidity.
Paint and varnish coatings must be heat-resistant, i.e. not destroyed when heated sun rays or other heat sources. In addition, they must be elastic, since when atmospheric conditions change, paint coatings dry out or swell, as a result of which cracks form, coatings wrinkle or peel off.
Types of wood finishing can be divided into the following main groups: transparent, opaque, imitation, etc.
When transparent In finishing, the surface of the wood is covered with colorless finishing materials that preserve or further enhance the texture of the wood. It is used for finishing furniture and high-quality construction products: windows, doors, panels made from valuable wood.
Transparent finishes are achieved by varnishing, polishing, waxing and coating with transparent films. When finishing by varnishing, varnishes are used that contain film-forming substances in organic solvents, solvents, etc.
Most often, polyester, nitrocellulose and urea-formaldehyde varnishes are used for finishing wood, and less often - oil and alcohol varnishes. Nitrocellulose varnishes dry well, produce a transparent, elastic, durable and fairly weather-resistant film that can be sanded well. Varnishes based on urea-formaldehyde resins form a film with a shiny surface that is quite transparent. The film formed by oil varnishes is elastic, durable, weather-resistant, but not decorative enough; alcohol varnishes produce a film with insufficient strength, weather resistance, and low gloss. Depending on the degree of gloss, coatings are classified into glossy, semi-glossy and matte.
When waxing, i.e. applying a mixture of wax and volatile solvents (white spirit, turpentine) to the surface of wood, a transparent film is also obtained, formed by a thin layer of wax (volatile solvents evaporate during the drying process). The wax coating is usually applied to porous wood (oak, ash). The wax film is soft, so it is covered with an additional layer of alcohol varnish. The wax coating has a matte surface.
When opaque finishing creates a film on the surface that covers the color and texture of the wood. Opaque finishes are used in the manufacture of school, kitchen, medical, built-in and children's furniture, doors, and windows.
To obtain an opaque coating, oil, nitrocellulose, alkyd, perchlorovinyl, water-based paints and enamels are used.
When painting with enamels with a high content of film-forming substances, glossy coatings, with less
They are semi-gloss, and when painted with oil paints they are matte.
Imitation finishing improves the appearance of products made from wood, the texture of which does not have a beautiful pattern. The main methods of imitation finishing are deep dyeing, pressing of textured paper with a pattern of precious wood, finishing with veneer, films, and sheet plastic.
The performance qualities of paint and varnish coatings must have a number of physical and mechanical properties: adhesion, hardness, heat, light and water resistance.
Under adhesion understand the adhesion strength of the paint and varnish coating to the surface of the wood, under hardness- resistance of the paint coating to penetration of a more solid body into it.
Water resistance- the ability of the coating to withstand the effects of water on the surface of the product. It plays a very significant role in the operation of carpentry products (window blocks, external doors) in conditions of variable humidity.
Paint and varnish coatings must be heat-resistant, that is, not destroyed when heated by sunlight or other heat sources. In addition, they must be elastic, since when atmospheric conditions change, paint coatings dry out or swell, as a result of which cracks form, coatings wrinkle or peel off.
The paint coating applied to wood performs 2 main functions: protective and decorative. In this article we will consider the main types of finishing: covering and glazing, which give a different decorative effect.
Glaze finish
When finishing products made of natural wood, as well as veneered parts, glaze finishing (sometimes also called transparent, translucent, tinted) is most widely used. This finishing allows not only not to hide the natural natural material - wood, but it is also beneficial to emphasize and refine the texture. The result of this finishing is a coating with visible wood texture.
There are 2 main options for obtaining this finish:
- Tinting wood with special tinting compounds followed by application of a transparent varnish layer (Tinting compounds or warriors(from die Beize (German) - pickling solution, wood dye, stain) have long been used in wood processing for coloring and refining. The texture of the wood is not hidden, but rather appears and is emphasized favorably.
- Painting with tinted (azure) varnish, to which the appropriate components have been added, giving the varnish the desired color tone.
Finishing technology with tinting compounds is widely used in industrial and craft furniture production for living rooms and kitchens, parquet and wooden stairs, interior doors(is a “classic” finish in the above products). This type finishing has a huge variety of options color solutions, and at the same time it is possible to achieve various staining effects, such as, for example, it is possible to emphasize the pattern of annual rings coniferous species(positive effect) and the pores of large-porous wood species (rustic effect), to even out the different shades of wood. In addition, it allows you to achieve the most uniform application of the tinting composition, thereby ensuring uniform coloring.
The technology of finishing with azure varnishes is less widely used in industrial and craft production for finishing doors, stairs, and furniture. With this finishing method, a less uniform color is often achieved than in the first case. This is due to the fact that the greater the thickness of the varnish layer, the more saturated the tone of the varnish film will be. This is especially true when using darker tones. This technology is most widely used in finishing wooden windows, where a professional finishing system includes the application of tinted varnish. The following options for producing azure varnishes with the desired color tone are possible:
- Adding pigments using a dispenser (on appropriate tinting equipment)
- Adding concentrates to the varnish directly at production (usually in quantities of 2-5%).
Covering finish
With this type of finishing, a completely opaque coating is obtained as a result of applying pigmented opaque materials to the surface of the wood, which completely hides the texture and color of the wood. In this regard, opaque finishing is used mainly for finishing products made from inexpensive wood, chipboard or fiberboard, the surface pattern of which is not original and valuable.
One of the main indicators that evaluate the efficiency of pigmented paints and varnishes used for opaque finishing is hiding power. GOST 8784-75 “Materials and paint and varnish methods for determining coverage” gives the following definition: “the coverage rate is taken to be the ability paint and varnish material make invisible the color or color differences of the surface being painted.” Covering power is measured in g/m2. GOST 8784-75 also provides methods for determining tensile strength. In other words, hiding power shows the amount of pigmented paintwork material (in g/m2) that must be applied to make the substrate invisible. The lower this indicator, the more opaque the material is (i.e., fewer grams are required to obtain an opaque coating). One of the main factors influencing the hiding power of paints and varnishes is the hiding power of the pigments included in the formulation. Since different pigments have different hiding power, pigmented materials (enamels and paints) various colors differ significantly in this indicator. To reduce consumption finishing material(enamel), as well as to eliminate the formation of defects during processing (“grinding”), pigmented primers can also be used.
Ordering the color of materials for opaque finishing is carried out according to the catalogues: RAL; NCS S, etc.
