Processing the product after assembly and preparing it for
finishing Protective and decorative finishing of products.

Surface preparation for finishing a product with paints and varnishes is divided into carpentry and finishing. Both of them distinguish between preparation for transparent and opaque coatings.

Carpentry preparation for transparent finishing. The surface to be finished is cleaned by mechanical treatment: planed with a sander, scraper, sanded with sandpaper. The surface prepared for transparent finishing must be smooth and even. Small cracks in the veneer and fiber breaks are repaired with putty matched to the color of the surface to be finished. Typically, putty is made from wood dust mixed with glue. Putty the surface before sanding.

On surfaces prepared for transparent finishing, defects that exceed the standards stipulated are not allowed. technical requirements for furniture. The surface roughness for finishing with a transparent coating should be no lower than 1632 microns. Carpentry preparation for opaque finishing. When preparing carpentry for an opaque finish, knots are drilled and sealed with plugs, and the surfaces are machined by planing, milling or grinding. The surface roughness for finishing preparation with an opaque coating should be within 200 ... 60 microns.

Furniture finishing refers to its processing, which improves the appearance of the product and protects it from environmental influences. When finishing, surfaces are covered with liquid finishing materials, lined with films and plastics, and decorated with carvings, burning, and applied patterns.

Depending on the finishing materials used, the techniques for applying them and processing the finishing, there are: transparent, opaque, imitation.

Transparent finish. A transparent coating is created on the surface of the wood with liquid or film finishing materials. If it is necessary to change the natural color of the wood, the surface is pre-treated with dyes. The simplest form clear coat - a thin layer of clear varnish applied to wood. In this case, the wood absorbs part of the varnish, and part of the varnish remains on the surface in the form of a transparent thin film. Wood absorbs varnish unevenly: looser layers absorb more varnish, denser layers absorb less. The clear finish preserves the wood grain.

An opaque finish covers the grain and color of the wood. An opaque one-color or patterned coating is created on the surface with liquid (enamels, paints, varnishes) or film (veneering) materials. Opaque coatings are applied to wood surfaces coniferous species and inexpensive soft ones.

Imitation finish. Artificially reproduces the texture and color of valuable wood on the finished surface of low-value wood. In terms of technology, imitation finishing differs from transparent and opaque in that the operation of applying texture is added. When simulating, for example, light hardwoods (birch, alder) to match the color and texture of walnut, the simulated surface is painted with a dye solution, then a pattern of walnut texture is applied to it. In this case, the birch texture is covered only partially, in places where the walnut texture is applied. Then the surface is primed and coated with clear varnish.

Special artistic decoration includes relief, applied, ornamental and typesetting decor: metal finishing.

According to their purpose, paints and varnishes are divided into three main groups:

materials for preparing the wood surface for finishing (putty primers, foam fillers);

materials that create the main paint layer (varnishes, enamels, paints, finishing pastes);

materials for refining paint and varnish coatings (leveling liquids, polishing pastes and polishes, grinding pastes, surface refreshing compositions).

Paints and varnishes are compositions consisting of a number of initial substances - components that perform different role in the paint and varnish material and the coating it creates. These components are divided into groups:

film-forming substances and binders - synthetic and natural resins, waxes, adhesives, drying oils, colloxylin, etc., which, as a result of physical and chemical processes, form a hard film that adheres well to the product material;

solvents – substances intended to dissolve film-forming substances and regulate viscosity paint and varnish material. Solvents can independently dissolve the film former or dilute the finished solution;

Drying agents – components that accelerate the drying time of coatings;

plasticizers - substances introduced into the composition of polymers and film formers, softening the film and making it more elastic;

fillers - substances usually added to increase the dry matter of materials;

coloring matter – pigments, dyes, mordants.

Dyes are powdery mixtures of colored organic matter, soluble in water, alcohol and other organic solvents and forming transparent solutions that change the color of wood without darkening the natural structure. Dyeing is used to enhance the natural color of wood, to imitate low-value species as valuable ones, and to tint varnishes. Dyes must be lightfast and have bright color, high dispersion, does not hide or obscure the wood texture and is easily dissolved in solvents - water, alcohol, acetone or other organic solvents. Based on their origin, wood solvents are divided into two groups - natural and synthetic.

Mordants are a type of dye that colors a part by reacting with tannins in wood.

Pigments are finely ground powders of one color or another. Pigments cannot attach themselves to the surface of the product being painted, and therefore are always used in a mixture with a solution of some film-forming material (glue, oil). Pigments are added to the binder to produce a light-resistant, opaque coating. Ready-made compositions from a mixture of pigment with a film-forming solution are called paints (glue, oil). Pigments are inorganic and organic.

Fillers are powders of inert substances introduced into paints and varnishes (paints, putties, primers) to increase the dry residue in these materials. Fillers must have high chemical inertness, not dissolve and, if possible, not swell in solvents and film formers with which they are used.

Fine powders are used as fillers rocks and pigments white(talc, kaolin, amorphous forms of crimnesin, spar, glass).

Solvents are organic volatile liquids intended for dissolving film formers (resins, cellulose ethers, varnishes) and plasticizers and bringing their solutions to working viscosity. Solvents can independently dissolve film formers or serve only to dilute ready-made solutions.

Liquids that do not independently dissolve the film former are called diluents in contrast to solvents. This name is conditional, since the same liquids can be diluents for some and solvents for other film formers.

Plasticizers are introduced into polymers and film formers to give them elastic properties and lower the temperature at which the polymer becomes brittle. The introduction of a plasticizer increases impact strength and provides greater elongation at break. At the same time, the plasticizer reduces hardness and tensile strength. Many non-drying or slow-drying liquids are plasticizers: alcohols, ethers, ketones, oils, etc.

Film-forming substances are capable, when applied to a surface in a thin liquid layer (in the form of a solution or melt), under certain conditions to form a thin and durable film that adheres well to the material of the product. Film-forming substances include drying oils and natural and synthetic resins. Drying oils – processed products vegetable oils, fats and organic products. They are used for making and diluting paints and priming the surface to be painted.

A primer is a suspension of pigment or a mixture of pigments with fillers in binder, which after drying forms an opaque, uniform film with good adhesion to the substrate and coating layers. The purpose of primers is to saturate the surface layer of wood, make it hard and dense, fill the pores of wood without significant shrinkage, and ensure high adhesion to the base and subsequent varnish coatings.

Pore fillers are compounds intended for rubbing into the pores of wood in order to close them before application. transparent coatings and forming, just like primers, the bottom layer of paintwork. Depending on the properties, the filler is applied to a pre-primed or unprimed surface. The filler layer helps reduce the consumption of paints and varnishes and reduce the subsidence of the coating into the pores during product operation.

Putties are thick pastes used to fill cracks and depressions in the surface of wood intended for opaque and, rarely, transparent finishes. Putties are prepared at the point of consumption, using glue, drying oil, resin, and varnish as a binder and film formers; as a filler - chalk, wood flour, small sawdust. Pigments or dyes are added to the putty to give it the desired color.

Varnishes are a solution of film-forming substances in organic solvents or water, which after drying forms a solid, transparent, homogeneous film. Depending on the nature of film formation, varnishes are divided into varnishes that form films only due to the volatilization of solvents (for example, alcohol, nitrocellulose), and varnishes that form films due to chemical reactions polymerization and semi-condensation, as a result of which they become insoluble (for example, oil, polyester). Varnish films protect the product from external influences, give them a more beautiful appearance, waterproof properties, etc. On the surface of the elements, a varnish layer of uniform thickness, color and gloss should be obtained, which has good adhesion to wood or underlying layers of primers, fillers and putties. The names of varnishes are based on solvents - alcohol or film-forming substances, for example oil, nitrocellulose, polyester, polyurethane, perchlorovinyl, etc.

Polishes are solutions of low concentration solid polishing resins, colioxin and plasticizers in a mixture of volatile organic solvents. Polishes are used to create an even, mirror-shiny transparent coating that reveals and deepens the natural texture of wood. There are alcohol polishes and nitro polishes.

Paints are suspensions of pigment and mixtures of pigments with fillers in drying oil, emulsion, latex, which form an opaque, uniform film after drying. Depending on the type of film-forming substances, paints are divided into adhesive, oil, emulsion, enamel, etc. When pigments are added to solutions of film-forming substances, coatings are given opacity and a color that depends on the color of the pigments. Pigments also change other properties of coatings. As a rule, the protective properties of paints are much higher protective properties corresponding pure film-forming films (varnishes). Increased protective properties of paints are obtained through the introduction of inorganic pigments.

Paints and the coatings they form must meet a number of requirements. In addition to the general requirements for good flow, fast drying, good adhesion and resistance to external influences, they must have specific color, degree of dispersion of solid particles (pigment and filler), high hiding power and shelf life.

Enamels are a suspension of pigment or a mixture of pigments with fillers in varnish, which after drying forms an opaque hard film with a different gloss and surface texture. The purpose of enamels is opaque finishing of wood products, including furniture, windows, doors, and parts of agricultural machinery. Depending on the composition of the main film-forming substances, enamels are divided into oil, alcohol, nitrocellulose, pentaphthalic, alkyd-alcohol, alkyd-urea, polyester, etc.

Film and sheet finishing materials.

In addition to paints and varnishes, various film and sheet materials, glued to the prepared surface of wood material. For this purpose, materials based on papers, synthetic resins, fabrics, metals, as well as combinations are used. various materials. Finishing film and sheet materials are divided into transparent and opaque, having their own adhesion to the substrate - wood material and not having it, requiring subsequent finishing after gluing and not requiring it.

One of the promising types of finishing of furniture products made from wood materials is pressing film materials based on papers (lamination). With this method, the protective and decorative coating is in most cases created using films impregnated with synthetic resins.

Films on paper based can be imitated, i.e. with wood texture or other pattern, or without imitations. The use of such films provides a replacement for planed and peeled veneer. Films based on papers impregnated with urea-formaldehyde resins can be pigmented, non-pigmented and decorative with imitation of various patterns.

Single-color films, pigmented and non-pigmented, are intended for gluing to wood materials as a primer layer under enamels. After gluing, the films are sanded and finished with enamels. As a result of their use, the consumption of putty and primer materials is reduced, and the number of enamel layers is also reduced.

Decorative films are also produced by impregnation with urea-formaldehyde resins with the addition of polyester resins or by applying them to the front surface of the film. In this case, a surface is obtained that does not require the application of paints and varnishes after pressing.

Films made of synthetic resins.

PVC films are transparent and pigmented (pigments and fillers are added), glossy, matte and semi-matte, rigid and elastic, available in thicknesses from 0.3 to 0.7 mm in rolls.

PVC films have weak adhesion to wood, so they are glued with perchlorovinyl glue, aqueous dispersion adhesives, latexes, and hot melt adhesives.

When finishing with pigmented films, two types of polyvinyl chloride films are used - the front one, which contains pigments and fillers, and a special adhesive film, to which epoxy resin is added in an amount of 4-6% of the total mass of the film. Epoxy resin improves the adhesive properties of polyvinyl chloride films and makes it possible to do without latex adhesives.

Textured polyvinyl chloride film is pigmented, with an applied wood texture, it can be smooth and embossed. They also produce textured polyvinyl chloride self-adhesive films, on the non-front surface of which a sticky layer is applied. Such films are glued by rolling and light rubbing to wood.

Decorative laminates.

They are made by hot pressing several layers of paper impregnated with artificial thermosetting resins. These plastics can be in the form of sheets of various sizes and in the form of rolls.

The facing layers of paper are impregnated with meshesin-melamine-formaldehyde resin, and all other layers with phenol-formaldehyde. In addition, to obtain a high-gloss surface on the exterior decorative leaf When forming a package, a layer of paper impregnated with melamine resin is placed.

Another type of plastic is rolled thin plastic with a thickness of 0.4-0.6 mm. If sheet plastic with a thickness of 1-1.5 mm is mainly intended for lining the faces of panel parts, then both the face and the edge are finished with rolls.

Decorative laminated paper is characterized by high light resistance and resistance to hot detergents, oils, gasoline, weak acids and alkalis. Therefore, it is widely used in the manufacture of kitchen, medical and children's furniture.

Finishing wood materials with decorative laminated paper requires the use of certain adhesives and technological regimes. To glue it to wood materials Epoxy, phenol-formaldehyde, urea, polyester and rubber adhesives are used. The plastic is glued hot or cold.

Supporting materials.

These include grinding materials, liquids for leveling and polishing coatings, oil removal compounds, bleaching and de-resining compounds.

The surfaces of dried paint coatings are leveled by grinding. Grinding is carried out with sanding cloths, less often with sanding pastes and sanding powders. When finishing, wood is sanded after applying (intermediate) and top coatings, i.e. after applying primer, putty, the first layer of varnish or enamel and the last layer of varnish.

Paint coatings are sanded wet method using liquid to cool the surface being sanded (for thermoplastic coatings - kerosene, white spirit, turpentine) and dry without the use of cooling liquids (for polyester coatings).

Polishing compounds are compounds designed to refine paintwork coatings and give them shine. These include leveling and polishing liquids, polishing pastes, and compositions for removing grease stains after polishing.

Resin-removing compounds. Softwood typically contains resin that protrudes into the surface or is in close proximity to it. The presence of resin makes it difficult to paint wood and can also damage the paintwork. Therefore, before finishing, the surface of coniferous wood must be deresined. For this purpose, liquid compositions that dissolve or saponify the resin are used. To dissolve the resin, acetone and tetrachloromethanol are used, and for saponification, calcium and sodium carbonate salts are used, i.e. soda and potash.

Whitening compounds. Used to bleach the surface of wood before finishing, to give it a lighter color in decorative purposes, aligning the color of the core and sapwood, removing stains. The best bleaching agent is titanium peroxide, which is harmless and suitable for bleaching all breeds.

Methods of applying finishing material.

The choice of method for applying finishing material mainly depends on the size and shape of the parts to be finished, the required thickness of the coating being created, and the level of mechanization of finishing processes at the enterprise. When making furniture, liquid finishing materials are applied to the surface to be finished using hand tools, a pneumatic sprayer, in an electric field, pouring, or dipping.

For small volumes finishing works finishing materials are applied with hand tools: a brush or a swab. To apply finishing materials to flat surfaces, bristle and hair brushes are used - round brushes.

To level the layers of liquid varnish on the surface to be finished, flat brushes are used. Special round brushes are used for applying varnishes to shaped surfaces, finishing carvings, etc. A tampon is made from furniture wool or knitting wool wrapped in linen.

Drying coatings.

During the drying process, liquid finishing coatings harden due to the drying agent (air, infrared rays and etc.). There is drying without forced action, which in turn contains three types of drying: convective with heated air, thermo-radiation with infrared and ultraviolet rays and accumulated heat.

Hardening of coatings, depending on the finishing materials used, occurs due to the evaporation of volatile solvents from the finishing material or the combined occurrence of the processes of evaporation of volatile solvents and the chemical transformation of the film-forming agent of the finishing material into a solid substance. In both cases, the drying time is influenced by the drying temperature. With increasing temperature, not only does the rate of evaporation of volatile solvents increase, but also the occurrence of chemical reactions accelerates.

Karelian State

Pedagogical University

Faculty of T&P

Department of specialties technical labor disciplines

and teaching methods (CTT and MP).

Essay

Protective and decorative finishing of wood products.

Group: 651

Student: Ageev V.S.

Teacher: Pronin A.A.

Public lesson by technology

"Wood finishing"

Technology teacher:

Ablyatifova U.S.

Lesson outline

using 5-b class technology

On the topic of:"Wood finishing"

Date: 12/08/2017

Lesson type: combined

Target: expand knowledge of wood finishing, familiarize students with safety rules when working.

Tasks:

Educational: introduce students to wood finishing; to develop students’ skills in performing finishing work: sawing, burning, drawing and varnishing.

Educational: to cultivate precision, attentiveness and accuracy in work, perseverance.

Developmental: development of aesthetic taste and creativity students; develop children's creative imagination through visual arts method deep dive into the material.

Planned results:

development of aesthetic consciousness through the development of the artistic heritage of the peoples of Russia and the world, creative activity of an aesthetic nature; formation of individual personal positions of students.

formation of communicative competence in communication and cooperation with peers; the ability to communicate when performing work or projects collectively, taking into account the common interests and capabilities of the members of the work team.

organize your workplace under the guidance of a teacher; determine the goal and draw up a plan for completing the task; develop practical skills and abilities.

Location: computer office, training workshop

Equipment: notebook, pencil, eraser, ruler, drawings, copy paper, tablet (alder, birch, maple), burning machine, jigsaw, brush, varnish.

Didactic material for the lesson: a selection of illustrations of works; samples of products on which all types of wood finishing are performed.

Teaching methods : explanatory and illustrated.

Technological lesson map

- Today we will continue our work on the study of wood. And before we start studying a new topic, let’s remember together the sequence of manufacturing wood products, using the example cutting board.

Before starting to study a new topic, I suggest you guess the topic of our lesson. Attention to the slide.

Having guessed the topic, students form an understanding of the content of the lesson topic.

Setting learning objectives

Today in the lesson we must study what types of finishes exist. And also what types we will work with (slide).

Students view presentation slides provided by the teacher.

Discovering new knowledge by students

Types of finishing:

1. Sawing with a jigsaw (slide). Any plywood product can be transformed, made beautiful and original with the help of a jigsaw. A jigsaw is a tool designed for cutting various contours from plywood, including curved ones. They can be used to cut both along the outer and inner contours.Safe work rules.

2. Burning is one of the types decorative finishing wood surface. Best material for burning - plywood. Before burning, grind the surface sandpaper. Then, using a burning machine, we begin burning. First along the outer contour, then along the inner.Safe work rules.

3. Drawing (gouache, watercolor). Any product can be made brighter and more original. The next type of finishing is drawing a picture using gouache or watercolor.Safe work rules.

4. Varnishing is a type of finishing in which the natural color and texture of the wood remains visible. The varnish protects the surface from moisture penetration and rotting.Safe work rules.

Primary consolidation of knowledge

A survey in the form of cards on the material covered.

Card

A jigsaw istool , intended forsawing out from various plywoodcontours , includingcurvilinear.

Burning is one of the typesdecorative finishingsurfaces wood.

Varnishing - typefinishing, at which it remains visiblenatural color andtexture wood.

Dynamic pause

The teacher shows the movement for warming up.

Carrying out movements after the teacher.

Creative Practical activities

Organization of student activities to apply new knowledge. The task is to complete technological map.

Reflection of activity

The teacher organizes reflection. Now let’s evaluate the lesson and the knowledge gained in general. On everyone’s desk there are emoticons, where red means the material has not been mastered, yellow means there are questions, green means the material has been learned well.

Students self-assess own activities. Also, students' work is reviewed and evaluated. In addition, students evaluate the level of knowledge acquired in the lesson.

Homework

Learn the technological map of the cutting board. Learn all safety rules when finishing wood.

Finishing- the final, final operation in the manufacturing process wooden products, which, for all their positive properties - beauty, hygiene, durability, etc. - have a big drawback: they are all susceptible to external physical conditions- temperature, air humidity, sun rays. Finishing is used to protect wood products from the influence of these factors. In addition, it should protect the material from pests and give the item a beautiful appearance. To do this, wooden products are coated with a layer of paint, enamel or varnish, covered with decorative film or veneered (veneer finishing), impregnated special compounds, protecting wood from rotting and pests. Protective coatings can be transparent or opaque. The former not only protect the wood, but also preserve its natural appearance, emphasizing the pattern (texture). They are usually used for finishing products made from valuable wood species and having a beautiful pattern. Opaque coatings are applied mainly to products made from low-value wood; At the same time, as a rule, they strive to make such coatings beautiful.

Opaque finish. This type includes the application of glue, oil or enamel paints to products. Adhesive paints are rarely used, so we won’t dwell on them. Much more durable and water-resistant coatings are obtained by painting wooden products with oil (alkyd) paints and enamels. They protect the wood not only from rotting, but also from warping, and therefore are especially suitable for painting furniture and objects in the kitchen and bathroom, as well as in the hallway and corridor. Painting with alkyd compounds is done with soft bristle brushes. Before use, it is recommended to heat the enamel in a water bath to 50-70 °C. Nitro enamels are applied using a spray gun in 4-5 layers. In this case, each previous layer must be sanded with fine sandpaper. The last layer is usually polished using a special paste. Keep in mind that nitro enamels should not be applied over oil-based paint since nitro enamel will dissolve the paint.

Preparing the surface for finishing. This operation includes sealing cracks, dents, fallen knots and other surface defects that were formed as a result of the previous machining. Large, deep cracks, crevices and voids are sealed wooden inserts on glue, small ones - with putty. Dents can be eliminated either by puttying or by generously wetting the jammed wood: having absorbed moisture, it will swell and the dent will level out. Having leveled the prepared surface, it is planed with a double plane in order to make it as smooth as possible. Upon completion of this procedure, the planed surface is wiped with a damp swab and, after drying, sanded with fine-grained sandpaper or pumice to remove the smallest fibers that make the surface rough. This operation is repeated several times. If the wood being processed is hardwood, then the lint is removed by scraping (for soft wood, the scraper is not suitable, since it does not cut, but only crushes the lint on them). The cycle is driven along the fibers. Places corner connections scrape along the seam at an acute angle to the direction of the fibers. The cycle is also used to remove products from the surface - furniture, doors, parquet, etc. - varnish and old paint before painting them. To make the process easier old paint can be softened by heating it with an iron through foil; the same can be achieved by wiping the surface with a mixture of acetone and gasoline (1:1).

Finishing preparation. This includes re-cleaning with cutting tools (if necessary), lubrication with pastes, sanding with sandpaper and pumice, de-resining the wood and priming the surface. The purpose of this preparation stage is to make the surface of the product as even and smooth as possible and to ensure strong adhesion of the paint to the wood. The order of finishing work is as follows: de-resining (for coniferous trees only), priming, greasing the ends, continuous puttying, sanding. After each of these operations, prolonged drying is carried out. Degumming is done using a solution of acetone in water (1:3) or a mixture of acetone and washing soda (1:4), or aqueous solution soda, heated to 60-70 °C. Use a rag or brush dipped in one of these solutions to wipe the surface of the wood, after which the remaining solution is washed off with warm water. At room temperature, the wood is dried for 12-16 hours. At the same time, it darkens, which is not significant for opaque coatings.

Padding increases the adhesion strength of paint to the surface of the product and reduces paint consumption. Primers (primers) for oil paints contain film-forming substances, fillers and pigments; it's actually the same Oil paint, but with a high content of drying oil and an appropriate coloring agent. The drying oil itself is also used as a primer. For nitro-enamel paints use special nitrocellulose or regular oil primers. There is no need to prime products that do not have large smooth surfaces. They can be coated with a thin layer of very liquid wood glue, after which has dried, lightly sand the surface with fine sandpaper and paint once.

Target puttying- obtaining a perfectly flat surface. This can be achieved using putty, which is applied to the surface of the product, filling all cracks, depressions and dents. After the applied solution has completely dried, the surface is sanded with fine sandpaper. Both of these procedures are repeated until the required surface smoothness is achieved. The quality of surface preparation can be assessed by applying a thin layer of slightly tinted putty to it and sanding it again. The painted putty on the convex areas is sanded off, as a result of which all the irregularities of the surface being treated will become visible. It should be borne in mind that the first grinding is performed both along and across the grain, and the last, final grinding is performed only along. Wooden products are putty with glue, oil, semi-oil and varnish putties. Adhesive putty can be prepared from liquid wood glue, chalk and drying oil. The prepared solution is applied in an even layer to the surface. A thin layer of it dries in 2-3 hours. Oil putty contains less liquid glue and more drying oil and paint. Thin layer of oil putty room temperature dries in 3-4 hours.

Finishing preparations are being completed grinding. Usually this operation is performed with sandpaper - first coarse-grained, and finally fine-grained. They usually sand along the grain, but hard wood can also be sanded across the grain. After proper sanding, the product can be painted. Typically the paint is applied 2-3 times, allowing it to dry for 24 hours, and then the applied layer is sanded. To make the surface layer shiny, apply one layer of oil varnish to it. The technique of applying paint and varnish coatings is described in the chapter “Painting works”.

When performing painting work, you often have to deal with painting defects: drips, folds, air bubbles, roughness, low shine of the surface paint film. Streaks and bubbles occur when paint is too thin or applied unevenly to the surface to be painted. The thickness of the paint can be assessed by the brush marks on this surface: if they spread within 2-3 minutes, then the paint is too thin; if after 10-12 minutes - normal; and if the marks do not disappear after 12-15 minutes, then the paint should be diluted, making it more liquid. The reasons for the formation of air bubbles may be the following: wet soil; too thick layer of paint; hard brush. The surface becomes pockmarked if painted at an air temperature below 18 °C. A rough film indicates that the surface to be painted was not cleaned of dust or that the product was dried in a dusty room. This can be removed by sanding and repainting. If the painted surface has a low shine, it means that either unrefined turpentine was used or it was used in excess. The shine can be enhanced by varnishing or sanding the surface.

Transparent finish. As already noted, this is a method of finishing carpentry products made from valuable wood. The transparent coating can be glossy, matte, velvety or mirror. With any method of obtaining such coatings (and there are many of them), first of all, careful finishing of the surface prepared for coating is necessary: it must be extremely smooth (i.e., without scratches, cracks and other defects) and absolutely free of lint. The process of preparing the surface for a transparent coating is the same as for an opaque one. But all operations must be carried out much more carefully.

Other finishing methods. There are ways to finish wooden products that are sort of between transparent and opaque finishes. As a result of their use, the natural color wood, but its pattern is preserved. In this way, for example, birch can be “made” into walnut, beech into mahogany. This is achieved by direct or mordant dyeing. In the first case, coloring substances penetrate the wood without chemically interacting with the substances contained in it, and determine the color of the surface being painted. During mordant dyeing, the dye chemically reacts with the tannic acids of wood, forming colored salts, which set the color.

With any type of dyeing, dyes can penetrate into the wood shallowly (0.3-1.5 mm) or to the entire depth of the material being painted. In the first case it is called surface dyeing, in the second - deep dyeing. For an amateur home craftsman, it will be quite enough to master only surface dyeing. More often than others, surface painting of wood with stain (stain) is used. It is a dye (usually water soluble) Brown. The stain does not cover the natural grain of the wood, but, on the contrary, makes it more contrasting and richer. Typically, stain is used for walnut coloring. The best “candidate” for this is birch, especially with small knots. In addition to birch, beech and spruce are also used. The most common, water-soluble stain, is sold in the form of a powder or liquid, ready to use. It must be diluted in soft water - rain, snow, river. If used for breeding tap water, you should add baking soda to it (1 teaspoon per 1-2 liters of boiled water) or a 1% solution of ammonia. The concentration of the stain solution can be 5-30 g per 1 liter of water, depending on whether the color should be more or less light. In addition to this factor, the intensity of the color also depends on the ability of the wood to absorb the solution. So, if you moisten it a little beforehand, the color will be more even.

The technique for applying stain is as follows. On vertical surfaces it is applied from top to bottom, avoiding contact with still free areas where stains may form. On horizontal surfaces, the stain is applied along the fibers, then across them, and finally again along the fibers. After drying, the surface is sanded with fine-grained sandpaper. Wood painted with water-soluble stain dries in 15 to 24 hours. A dry painted surface can be wiped with cloth or other similar material to remove dry, unabsorbed dye particles from the surface.

In the manufacture of various joinery products they use different types wood finishing. They are divided into the following groups: transparent and opaque, imitation, special. Let's consider each of those used.

Transparent finish

A transparent finish is obtained by applying, most often, colorless, as well as painted transparent finishing materials to the surface of wood. This coating preserves and emphasizes the original structure of the wood. Most often, this is used for products made from solid wood of various species, fiberboard and particle boards, as well as products lined with various types of veneers.
A clear finish is achieved by varnishing, waxing, polishing or filming.
If we look at varnishes, they contain solvents, film-forming substances, and so on. That is, for finishing wood they use:
urea-formaldehyde varnishes that form a film with a shiny surface;
polyester nitrocellulose varnishes, quickly drying, producing a dense, transparent, elastic and resistant to various atmospheric influences film.

Much less often, wood is coated with oil and alcohol varnishes. The former form a weather-resistant, durable film, but does not have the proper decorative effect, while the latter’s film is fragile and does not have a bright shine.
Varnish coatings are divided according to appearance for four classes. For example, first class coatings should not have visible defects and, at the same time, their surface should be even and smooth. Also, painting defects or whitening in the pores should not be visible. Also, varnish coatings differ in operating conditions, that is, on how resistant the coating is to water, temperature, and atmospheric conditions; they can belong to one of eight groups.

Opaque finish

Types of wood finishes include opaque finishes. It is obtained by applying opaque materials containing pigment to the surface of wood. It completely hides the natural texture and natural color of the wood. Typically, this finish is used in the production of furniture, built-in equipment, as well as for covering the frames of windows and doors.

Imitation finish

This type of finishing improves appearance wood products, and even if it is made from ordinary types of wood, it becomes more expensive and valuable. Typically, imitation finishing is used in the manufacture of furniture and so on.
Imitation finishing can be achieved by deep coloring, applying a pattern that conveys the texture of wood of a certain type, pasting with paper with a suitable ornament, lining with wood-like plastic, or pressing resin films.

Special wood finishing

Special wood finishes are obtained by applying a layer of molten or powdered metal to the wood, called plating, and by coating it with molten resins or other materials. This can be carving, inlay, burning, embossing. As a rule, such wood finishing is not used en masse, but is used only in bleaching products produced to order.

Types of joinery finishes. Wood finishing is carried out in order to give the joinery an attractive appearance and additional protective properties. Exist the following types finishes: transparent, opaque, imitation, special.

Transparent finish while maintaining or enhancing the manifestation of the wood texture pattern, it is obtained by waxing, varnishing with oil, alcohol, nitrocellulose, polyester and urea-formaldehyde varnishes, and polishing. All types of transparent coatings are used on both natural and tinted wood surfaces.

Opaque finish, hiding the wood texture is achieved by covering the surface with oil and nitrocellulose paints and enamels. Gilding and bronze plating are also used for finishing decorative wooden products.

Imitation finish allows you to improve decorative properties wood of non-valuable species to give it the appearance of valuable wood or other materials. The main methods of obtaining an imitation finish are: deep dyeing, applying a pattern to the texture of valuable wood, cladding wood with various materials.

At special finishing a finishing layer of metal (metallization), molten resin and other materials is applied to the surface of the wood, and various decorative works directly on the surface of wood (carving, embossing, inlay, burning).

Decoration Materials used for finishing wood. To finish the surface of wood, paints and varnishes (paints, varnishes, drying oils) and auxiliary substances (thinners, solvents, driers) are used.

paints and varnishes They are multicomponent compositions that, when applied in a thin layer to the surface of products, can dry to form a thin film. They are used to produce protective and decorative coatings.

Film-forming substances are the main components of paint and varnish material. They are capable of polycondensation or polymerization reactions. Polycondensation film-forming agents include alkyd (glypthal or pentaphthalic) and other polyester resins, as well as phenol-formaldehyde, epoxy and polyurethane resins.

TO polymerization film-forming materials These include resins based on vinyl chloride, acrylates, and methacrylates. Natural resins (rosin, asphalt, bitumen, pitches), cellulose ethers (nitrate, acetate) and oxidized oils (linseed, tung, tallow), called drying oils, are used as film-forming agents. Drying oils oxidize and polymerize to a solid state in air. To accelerate polymerization, catalysts - driers - are added to drying oils.

Lucky are solutions of film-forming substances in organic solvents.

Paints, primers, putties are a suspension of pigments and fillers in varnishes or drying oils. They may contain special additives - plasticizers, driers, hardeners, stabilizers and emulsifiers.

Paints made with varnish are called enamels, and those made with drying oil are called oil paints.

For gluing or hot pressing onto the surface of wood products, sheets and roll materials based on papers, fabrics, synthetic resins, metals, composite materials.

Technology and equipment for wood finishing. The technological process of wood finishing consists of the following stages:

carpentry preparation of wood surface for finishing;
applying paint and varnish;
refining the paintwork.

The technological process for opaque finishing is practically no different from the production of transparent finishing. Difference technological processes consists of preparing the surface for finishing and the materials used for finishing.

To obtain an opaque finish, the surface roughness of the product must be at least class 10 according to GOST 7016-75. For an opaque finish, thicker compounds are used that completely cover the wood texture. For transparent finishing, compounds are used that enhance the texture of the wood from which the product is made.

There are the following methods of applying paintwork:

spraying;
dipping;
roll;
Lakonaliv.

Spraying production of paints and varnishes can be manual or mechanized. At enterprises manual The spraying method is carried out by a worker moving the sprayer inside a specially equipped chamber, which protects the finishing rooms from air pollution with paint mist generated when the installation sprayers operate at the required speed.

Mechanized The method of spraying paints and varnishes is used in automatic and semi-automatic finishing lines using spray nozzles operating in automatic mode.

The following methods of applying paints and varnishes by spraying are also used: with airless spraying and spraying in an electrostatic field.

Method airless spray is based on the use of nozzles with a nozzle with a diameter of 0.3-0.5 mm, to which paint and varnish material heated to 70-100°C is supplied under pressure of up to 4.5-6 MPa.

When leaving the nozzles, a pressure drop occurs, and the highly volatile part of the solvents included in the paint and varnish material evaporates. As a result, it is divided into tiny particles that settle on the surface to be finished.

Method spraying paints and varnishes in an electrostatic field used for finishing lattice products and products of other complex shapes.

The method is based on the principle of imparting a positive electrical charge to the treated surface, and a negative electric charge to the finishing composition, which causes the attraction of the finishing composition to the surface being finished due to oppositely charged particles.

To obtain a high-quality coating using this method, it is necessary that the electrical resistance of the finishing composition is in the range from 1 to 10 MOhm and its components are uniformly electrically charged. Therefore, finishing compounds intended for electrostatic spraying should not contain water or metals.

Way dipping used for painting solid wood parts. When dyeing by dipping, the products are immersed in a bath with a dye solution heated to 50-70°C for 20-30 s.

At the same time, the speed of removing products from the bath to avoid the formation of smudges is low. After this, the products are placed over a mesh to allow excess solution to drain from the surface, and then wiped with a damp swab.

Way roll forward carried out mechanically using roller machines. For example, the PKB MMSC-1 machine for applying dye with rollers consists of a frame, a feed roller table, four application and four metering rollers, three rubbing pads, a drum for cleaning the painted surface, a container for dye solution, four collectors, pressure rollers and a tray.

The rolling method is also used when applying paints and varnishes in installations with rotating drums. This installation works as follows: a metal drum, through the side walls of which a horizontally located shaft connected to the drive passes, is loaded with the parts to be trimmed to 3/4 of its volume. After which it is poured required amount paint and varnish composition (at the rate of up to 150 g per 1 m2 of surface to be finished). When the drum rotates at a speed of 35-45 rpm and constantly mixes and moves the parts in it, the varnish is evenly applied to them. The rotation of the drum continues until the varnish is completely dry.

Method Laconaliva consists of creating a curtain of varnish using nozzles (filling heads), which are part of varnish-filling machines. The parts to be finished, passing through it, are covered with a thin, even layer of paint and varnish material. The width of the varnish curtain must be greater than the width of the part being finished. Varnish filling machines come in single and double head designs.

At drying ready carpentry The liquid layer of paint and varnish material turns into a solid coating. The hardening speed depends on the type of paint and varnish material, layer thickness, drying method, and parameters of the drying agent.

Curing of applied various methods coatings, depending on the composition used, can result from:

evaporation of volatile solvents from liquid paints and varnishes;
chemical reactions;
melting and cooling of paint and varnish compositions.

Drying paint coatings can be natural or artificial. In this case, artificial drying is divided into convection drying, accumulated heat drying and thermoradiation drying.

Convection drying involves drying products with heated air in batch chambers or pass-through type with an air temperature of 40-60°C for nitro-varnish coatings and 60-80°C for polyester varnishes.

Drying is carried out in several stages at the following temperature conditions:

1) 25-45°C;
2) 45-55°C;
3) 55-65°C.

The circulation speed of the drying agent is 0.5-1 m/s.

For drying paint and varnish coatings by convection, drying installations of the PKB MMSC-1 type are used. Air circulation in this installation is provided by a fan, and heating is provided by plate heaters.

Stored heat drying consists in the fact that the parts to be finished are preheated and then applied to them paint and varnish composition. The heat contained in the wood is transferred to the varnish coating from the underlying layers to the upper ones and contributes to its rapid drying.

Thermoradiation drying consists of irradiating paint and varnish coatings with infrared rays generated by incandescent lamps, panels and emitters various types. The operating principle of this method is that infrared rays with a length of 1-4 microns penetrate through the liquid layer of varnish, heating the wood. Heated wood transfers heat to the varnish coating from the lower layers, drying it.

Refinement of paint and varnish coatings consists of eliminating uneven paint coatings and local defects. This technological operation performed by the method grinding.

Grinding happens dry And wet, intermediate(after applying layers of paint and varnish material), leveling. Sanding coatings on belts grinding machines type ShLPS and vibration grinders type ShLV2.

After leveling the coatings by grinding, abrasive marks up to 3 microns deep may remain on the surface to be finished. Their elimination is achieved by polishing on belt or drum machines using paste No. 290 (liquid or solid).