Finishing of wood products. Front finishing of wood products Types and methods of finishing wood products
Types of joinery finishes. Wood finishing is carried out in order to give the joinery product an attractive appearance and additional protective properties. There are the following types of 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 no wood 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).
Finishing 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.
Paint and varnish materials 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 substances include alkyd (glyphthalic or pentaphthalic) and others 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 in air oxidize and polymerize to a solid state. 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 paint and varnish products 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 spray method paint and varnish materials 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, which settle on the surface being 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 electrical resistance finishing composition was in the range from 1 to 10 MOhm and its components were uniformly electrically charged. Therefore, finishing compounds intended for electrostatic spraying should not contain water or metals.
Way dipping used for painting parts made of solid wood. 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: metal drum, through side walls which runs through a horizontally located shaft connected to the drive, 3/4 of the volume is loaded with the parts to be finished. After which it is poured required quantity 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 hard surface. 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 and artificial. In this case, artificial drying is divided into convection drying, accumulated heat drying and thermoradiation drying.
When convection drying, products are dried with heated air in periodic or pass-through chambers 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 using the convection method drying plants type PKB MMSC-1. 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 a paint and varnish composition is applied to them. The heat contained in the wood is transferred varnish coating from the underlying layers to the upper ones and promotes 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 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 is performed using 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 applying polishing on belt or drum machines using paste No. 290 (liquid or solid).
Security questions
- 1. How are woodworking industries divided?
- 2. Define the technological process.
- 3. What is an operation that is part of the technological process?
- 4. What types of woodworking workshops do you know?
- 5. Why is wood processing waste processed?
- 6. What types of modern wood composite materials do you know?
- 7. List the main types of carpentry joints.
- 8. What types of joinery assembly are there?
- 9. What operations does the joinery assembly technology include?
- 10. What operations does the production of laminated wood involve?
- 11. Name the equipment used in the production of laminated wood.
- 12. For what purposes is wood bending used?
- 13. What bending methods do you know?
- 14. List the main types of finishing of wood materials.
- 15. Name the main materials used in wood finishing.
- 16. What equipment is used for finishing wood materials?
Open lesson on technology
"Wood finishing"
Technology teacher:
Ablyatifova U.S.
Lesson outline
using 5-b class technology
On the topic:"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 works: sawing, burning, drawing and varnishing.
Educational: to cultivate precision, attentiveness and accuracy in work, perseverance.
Developmental: development of aesthetic taste and creative abilities of students; develop children's creative imagination through the use of fine arts using the method of deep immersion in 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 aesthetic character; 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.
Venue: computer room, training workshop
Equipment: notebook, pencil, eraser, ruler, drawings, copy paper, tablet (alder, birch, maple), burning machine, jigsaw, brush, varnish.
Didactic material To training session: 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 you start studying 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 species 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, sand the surface with 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. Next view finishing - 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 activity
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 their own performance. Also, students' work is reviewed and evaluated. In addition, students evaluate the level of knowledge acquired in the lesson.
Learn the technological map of the cutting board. Learn all safety rules when finishing wood.
Types of finishing can be divided into the following main groups: transparent, opaque, imitation, etc.
With transparent finishing, the surface of the wood is covered with colorless finishing materials that preserve or further reveal the texture of the wood. It is used for finishing furniture and high-quality construction products: windows, doors, panels made of 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.
Varnish coatings are divided into four classes by appearance, and into eight groups by operating conditions (depending on the resistance of the coatings to atmospheric conditions, water, and temperature).
A type of transparent finish is polishing with 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 transparent film, 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.
With an opaque finish, a film is created on the surface that covers the color and texture of the wood. Non-transparent finishing is used in the manufacture of school, kitchen, medical, built-in and children's furniture, doors, and windows.
To receive opaque coating use oil, nitrocellulose, alkyd, perchlorovinyl, water-based paints and enamels.
When painting with enamels with a high content of film-forming substances, glossy coatings, with a smaller amount - semi-gloss, and when painted with oil paints - matte.
Imitation finish enhances appearance 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 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 the surface of wood, while hardness refers to the resistance of the paint coating to the penetration of a harder body into it.
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.
The final stage in creating wood carvings is their finishing. This process is quite labor-intensive, but you don’t need to spare any effort or time on it. Only well processed carved wooden product acquires decorative expressiveness and is truly pleasing to the eye. It must be borne in mind that, first of all, the finishing results depend on how competently the work is done with the cutter. So, for example, if a dihedral notch is made in violation of the “face to face” rule, then only the same cutter can remove the flaw at the bottom of the groove, but its size will change. A file and sandpaper cannot achieve a clear edge. It will take a painfully long time to remove burrs in concave recesses if the “chip to chip” rule was violated during their execution. IN hard to reach places You need to cut off the shavings especially carefully, as the masters figuratively put it, “remove the meat.” You can imagine what will happen in the end if you do not cut the meat from the skin during dressing. Apparently this is where this expression originates.
Usually a novice carver has a desire to eliminate surface unevenness with sandpaper. But when this fails, he is forced to take up the cutter again and dulls the tool blade on the micro-emery particles that have cut into the wood.
Therefore, advice: Do not touch the sandpaper until you have used all the capabilities of the file and cutter.
The finishing process consists of the following stages: sanding the wood, polishing it, tinting it and finally coating it.
Machines do not make mistakes, so all Guardian entrance doors are made with minimal tolerances and gaps. The door leaf and frame must be painted powder paint on both sides, and we do this regardless of the type of finish, so that the door serves you for a long time - does not rust or fade in the sun. We make a door once, and it serves you for many years.
Finishing of wood products is the creation of protective and decorative coatings on their surface. Tree under influence environment can change shape and size, fade (fade, turn grey), and can be damaged by insects (shashel, etc.). To protect the wood from unwanted influences, it is coated with a thin layer of varnish or paint; this also improves the appearance of the products, reveals the texture of the wood, and changes its color.
Safety rules at work
- When applying paint and varnish coatings, wear gloves.
- Apply coatings only in well-ventilated rooms (vapors from varnishes and paints are harmful to health).
- Electric heating devices must not be used in the room where work is being done.
- After finishing work, wash your hands thoroughly with soap and water, and if the paint does not wash off, wash your hands with vegetable oil or drying oil.
Product finishing
- Finishing of wood carpentry can be opaque, transparent and artistic. With opaque finishing, a film is created that covers the color and texture of the wood, while opaque finishing is used in the production of windows, doors, kitchen and medical furniture.
- Paint and enamel are applied to the surface with brushes, rollers, nitrocellulose - with brushes and sprayers, water-based - with brushes, rollers, sprayers, paint and enamel are applied to the prepared surface of the product in two or three layers. Each layer is well dried and sanded, and then the next one is applied.
- During transparent: the tree is covered with colorless materials. Finishing materials should maintain or even more clearly show the texture; for transparent wood processing, various varnishes (polyester and nitrocellulose) are used, less often - oil ones. Often before applying transparent coatings, the wood is tinted with transparent dyes, and the texture becomes more expressive and beautiful.
- Polyester varnishes are used only in production conditions; they form high-quality insoluble films.
- Nitrocellulose varnishes are applied with a brush and swab, they can be poured and sprayed; small parts are dipped in varnish. Nitrocellulose varnishes dry well and provide a durable, elastic, transparent and fairly weather-resistant film. Oil varnishes, like oil paints, applied with brushes and rollers. The film formed by these varnishes is more durable, elastic and, most importantly, weather-resistant, but unfortunately not so beautiful, in addition, oil-based varnishes take a long time to dry: from 8 to 24 hours.
- To provide high quality coatings, the surface is prepared for finishing: knots, cracks, fiber breaks and other defects are sealed, sanded, primed.
- Varnishes are applied to a dry, dust-free surface in even layers, approximately three to six times. After applying each layer, the surface is dried, sanded, and then a new layer is applied. Finishing is considered good quality, if the surface of the product has a uniform and even shine.
The paint coating must meet the following requirements:
- Be moisture-resistant, heat-resistant and light-resistant, hard and elastic, reliably adhere to the surface;
- Do not have wrinkles, bubbles, smudges, be uniformly glossy over the entire surface;
- Improve the appearance, reveal the wood texture using the transparent method;
- Cover the surface of products made of low-value wood with an even layer with opaque coatings.
Wood finishing - wood carving, inlay, burning, painting, etc. The artistic method gives products a beautiful appearance, and is used in the manufacture of furniture, boxes, souvenirs, children's toys, and wooden utensils.
Finishing wood products video - instructions
