Painting work can not be started immediately after you have decided on the choice of primer and paint. The main condition is proper surface preparation for painting. This work should be carried out taking into account the structure of the area over which paint will subsequently be applied. The performance of this work is strictly prohibited. Indeed, on an unprepared surface, the coating will lie unevenly. And all the flaws will be striking.
Plastered surfaces
Cement is applied to the walls of bricks or blocks. This is a cement-sand mixture. With a wooden trowel, it is smoothed along the wall. As a result, a sandy rough surface is formed.
It must be remembered that in the cement mixture are alkaline substances. They can destroy the paint coat. Over time, the coating ages and erodes, cracks may appear. If you plan to apply a layer of paint on top of it, you need to know what material it was applied to. For example, before applying the paintwork it is necessary to withstand the surface for 2-3 months.
In a moderately mild and mild climate, the use of water-based paint is allowed even before the surface has completely dried. Due to the permeability property, when the coating is dry, the walls will already be painted. The use of water-based paint is also allowed in adverse climatic zones. But its use is possible only after complete drying. In addition, it is necessary to properly prepare the surface for painting with aqueous compounds.
Concrete surfaces
In construction, the most common material is concrete. It consists of many ingredients, the main ones being sand, Portland cement, water and rock mass.
Wet concrete is an alkaline mix. Reinforced concrete structures may suffer due to corrosion of metal elements. Often, concrete surfaces can be destroyed due to the ingress of chlorides. The carbonization process can also negatively affect it - at the same time it drops below 10 pH (degree of alkalinity).
Fiber concrete is also often used. It differs from ordinary in the presence of sawdust or asbestos in the composition. These additives replace sand, which affects the overall weight of the structure. It is significantly reduced.
Glass concrete is sometimes used, which includes special glass fibers. They strengthen the material, are able to withstand the negative effects of alkali. Often it is used for cladding.
Concrete mixed with pebbles is reminiscent of coarse plaster, which is put on a surface.
Using a brush, check the stability of the stones in the total mass. Make sure they hold well. It should also be remembered that when preparing the surface it is not recommended to make a deep relief. Indeed, so the paint consumption is significantly increased.
Sometimes concrete structures are treated with turboline. This is a smear with its own color. Such material is characterized by resistance to various natural phenomena. It can be optionally covered with varnish or paint. In this state, the coating can retain its properties for more than 10 years.
Preparation of concrete surfaces for painting is simple, it is enough to clean the material with high quality.
Brick wall preparation feature
It is possible to paint a brick wall only six months after its construction. If the coating on the brick was done in the fall, the drying time must be increased by another 3 months. At the same time, remember that the thickness of the dry layer when preparing the surface for painting should be about 2-3 cm.
Having decided to paint a brick wall, it is necessary to apply a coating. Without it, at the joints of bricks there will be little adhesion of the paint and the base. This means that after the building material freezes, the coating may break off at this location.
Reliable, strong technical brick is characterized by a low absorption rate. It is used to decorate the space around windows or above doors. Often it is used in wet areas. Such a surface is not painted, because the paint on it does not adhere well.
Coating a brick with a thick layer of paint is not recommended, because it contains alkali. Glassy and polished material is often used in decoration, it is not stained. Its surface is covered with a layer of glass immediately before firing.
Features of the surface of concrete blocks
Modern buildings are often built from concrete cinder blocks. They consist of a large amount of furnace slag and coal litter. They are used for the manufacture of partitions, interior decoration of ceilings. Cinder blocks are characterized by a high absorbency, texture. For exterior decoration this material is not used.
This building material contains alkali in large quantities, so it is not recommended to apply a thick layer of paint on its surface. Concrete can only be painted when it is completely dry.
Insulation blocks are made of Portland cement, sand, sawdust. They are characterized by a high insulation rate. Compared with concrete, this figure is increased 3 times.
Often there are internal voids in the blocks. They significantly increase soundproofing properties. The insulation blocks also have good absorbency, so they can be coated with emulsion paint. This layer will additionally perform a protective function.
Features of the preparation of structures from concrete blocks
Preparation for painting a concrete or gypsum surface necessarily involves cleaning the surface of dust. The same procedure is carried out with a plastered plane. After the material is cleaned with pumice or sandpaper. This will eliminate roughness and various defects.
After carefully inspect the structure for cracks. If they are present, they are shut up. To do this, they are deepened by a few millimeters, moistened with water and sealed with gypsum mortar or putty. When the solution dries, it must be leveled with a special grater.
Features of surface cleaning and paint selection
Preparation of plastered surfaces for painting needs to be carried out sequential work. First, the spray of the solution is removed (cement-sand, gypsum, lime).
If plaque appears on the plaster, it is cleaned with a stiff nylon brush. If holes or cracks are present, they must be coated with a special putty. After drying, the surface is ground and dust is removed with a damp cloth.
The new plaster contains a large amount of alkali. For this reason, do not choose solvent-based paints and varnishes. If the application of some organically soluble composition is envisaged, it is necessary to wait for complete drying. After you can apply the primer.
Masonry needs a particularly thorough surface preparation before painting. It must be durable, clean and dry. Be sure to remove drops of cement and plaque. If the structure has recently been erected and has not previously been painted, you can immediately begin painting after cleaning. If the surface has previously been painted, you must first remove the previous layer.
Sometimes the surface is affected by fungus or mold. It must be pre-treated with special fungicides. If the first time the application did not give its result, the procedure is repeated until the fungus is completely destroyed.
The old paint is removed, all flaws and cracks need to be coated, cleaned.
Surface preparation of concrete slabs
All plates have a porous structure, so they are often painted with emulsion compositions. Surface preparation for water coloring consists in thorough cleaning and drying.
If the unpainted structure has been outdoors for a long time, it is necessary to clean it from lichens, mold and algae, and treat it with fungicides.
The technology for preparing a surface for painting previously exposed to paint is simple. If the condition of the previous layer is satisfactory, similar paints and varnishes can be used.
If the initial coating adheres well, it is enough to wipe it with a 2% soda solution. In the place where the paint has peeled off, it must be completely removed.
The old layer can be removed using a blowtorch, a special wash. You can use special hair dryers.
Features of a wooden surface
Preparation of wooden surfaces for painting requires careful implementation of sequential work. Wood does not show much resistance to the negative effects of the environment. For this reason, wooden structures are often in need of repair. This is especially true for the exterior surfaces of windows, doors, plum boards and fronts. Under the influence of moisture, the wood tends to swell, and at high temperature - to dry out. Wooden structures are subject to the development of rot and insects.
Almost all wooden structures at the manufacturing stage are covered with protective equipment. But before painting, you need to make sure the quality of the application of this tool.
Preparation of a wooden surface
If the primer has soaked the wood well, you can treat the surface with fine-grained emery paper, clean it of dust and apply a second coat of soil.
After drying, re-grind and clean from dust with a cloth. It is pre-impregnated with a composition that attracts dust or white spirit.
The surface of a softwood product is best covered with an oil primer. Often used and acrylic composition, which can be diluted with water. Remember that the primer must be applied in a thick layer. All end surfaces must be carefully processed, because on them the fibers absorb soil the best.
After the soil has dried, putty is carefully applied. Minor defects close up with a soft composition. After drying, the plane must be cleaned with fine-grained sandpaper.
If the surface will subsequently come into contact with the ground, this area must be treated with a colorless special agent. It prevents the development of the process of decay. Carefully read the instructions, this tool should be compatible with the selected paintwork material.
If the surface has been previously painted, it is recommended to completely remove the old paint coat. After you must follow the above instructions.
Metal surface preparation
Paint is an additional layer that is able to protect the metal structure from corrosion. In production, the metal is coated with a thin layer of oxide. If the metal product is in contact with the environment, the oxide film is eroded and oxidized. It turns yellow and peels off with paint. Experts recommend removing this oxide layer before painting and applying the paintwork directly to the metal. It can be cleaned using blasting.
Before painting, you must pay attention to the surface profile. It can be smooth, rough and medium. Profile processing can be carried out with coarse particles or with a sandblasting machine.
If the metal surface has already been coated with paint, the preparation of metal surfaces for painting is to remove various defects. A second coat is recommended to be applied with a better material.
GOST
An important component of the correct finish is surface preparation for painting. GOST 9.402-80 describes the correct sequence of work, the required number of paints and varnishes in a particular case.
This standard describes the technical requirements for the surface quality of products made of ferrous, non-ferrous metal and alloy. GOST necessarily includes information on the features of the technology for preparing a metal surface before painting.
Output
Proper surface preparation and application of paint is the key to the perfect appearance of the product for a long time.