Wood is an excellent building and decoration material. Environmental friendliness and beauty distinguish it from any synthetics. However, there are also many shortcomings in natural raw materials. Wood is afraid of the bright sun, dust, winds. Mold and insects can damage it, and the porous structure contributes to enhanced moisture absorption. To protect against aggressive environmental factors and reduce the consumption of paints and varnishes, special primers are used.
Wood processing purpose
The primer for wood is a liquid on an acrylic, alkyd, mineral and oil base containing resins, plasticizers, glue, antiseptics, pigments and other components that provide surface preparation for further paintwork or varnishing. The choice of composition depends on the species of wood and the expected conditions of its operation, the type of subsequent staining.
When processing lumber, the primer performs a number of tasks:
- disinfects, destroying mold spores, putrefactive bacteria, parasite larvae;
- impregnates the top layer of the material, bonds the fibers, fills the pores, smoothes the pile and creates a protective waterproof film that prevents erosive processes, swelling and destruction;
- depending on the purpose, evens out the color, emphasizes the natural woody pattern, hides stains;
- improves adhesive qualities, helping to ensure optimal adhesion of surfaces;
- Saves the consumption of varnishes and paints.
Primer compositions differ in penetration depth, time required for complete drying, and the degree of protection created. Depending on the characteristics, some tools are suitable only for internal work, others are used for finishing wooden parts, walls of buildings and buildings from the outside.
Types of primers
By composition, they are classified into:
- Acrylic Without exaggeration, they are considered universal. They have an emulsion structure, diluted with water. They are used for processing not only wood and wood-based materials, but also concrete plaster, brickwork. Great as a base for acrylic paints. Penetrate deeply, absorb quickly and well. Odorless, non-toxic, do not cause respiratory tract irritation during use. Drying time is about 3 hours. Depending on the porosity of the wood, the acrylic primer is applied in one or more layers. The disadvantage is low moisture resistance, freezing at sub-zero temperatures, which is why it is used mainly for internal work.
- Alkyd. These types are well suited for application on wooden, metal surfaces, cardboard, plastic, plaster. They are enamels, which contain more solvent. They create a resistant waterproof film on the surface during single-layer application. Alkyd primer provides good adhesion, can withstand low temperatures in the street, wear-resistant, therefore it is recommended for external work. It can be applied to previously painted surfaces. Drying time is about 12 hours. The disadvantage is a shallow impregnation of the material and a pungent chemical smell that disappears for a very long time.
- Polyurethane This type of composition is a mixture of epoxy resins and special solvents, is more expensive than others and is suitable for surface treatment before applying varnish. Creates a perfectly smooth transparent or pigmented coating. It does not differ in penetration depth and durable surface strengthening, it is toxic. Polyurethane primers are of several types and are not practical for wood processing. They smell very much and dry for a long time. It takes about a day to completely dry the surface.
- Shellac. They are used for leveling and fixing the natural color of wood, isolating places from which the resin flows, smoothing the pile. For these reasons, shellac is well suited for coating fresh material and diluting soluble impregnating compounds.
- Drying oil. It is produced on the basis of mineral or vegetable oils, and is used as a base for oil paints. It is well absorbed in solid finely porous wood species, protects surfaces from mold. To increase hydrophobic properties, wax is added to some oil formulations. With the help of drying oil, both external priming works on wood and the processing of internal surfaces are performed.
- Glue. For the treatment of wooden surfaces inside work and storage rooms, garages, sheds, inconspicuous places in the house, a rather practical composition based on PVA glue and water is used. It is prepared simply: 1 part of the glue is diluted with 2 parts of water, the suspension is thoroughly mixed, a little chalk is added.
Manufacturer, brand | A type | Volume l | Price, rub |
Belinka base | alkyd | 1 | 605 |
V33 | antiseptic | 2,5 | 1 219 |
Tikkurila Otex AP | alkyd, adhesive | 0,9 | 850 |
Grid | acrylic | 10 | 170 |
Teknos futura | primer paint | 9 | 6 336,60 |
Crucial are not only price, quality, composition, but also color. The primer for painting with enamels and oil paints can be matte, and varnishing requires a completely transparent layer, emphasizing the natural pattern. Many colorless soils are used as an independent coating in the decoration of decorative details of the interior, furniture.
Work
Priming wood is not difficult. The main thing is to properly prepare the surfaces for processing: thoroughly clean the remaining paint, varnish from the old ones, sand, rub small debris and dust. If you plan to apply new paint of the same color and base with the old one, it is not necessary to completely sand the surface, it is enough to remove the exfoliated layers.
The resin is cleaned from a fresh tree, the surface is ground, the breakaway parts are cut. Then smooth out irregularities, recycle, fill cracks and seams. Grease, dirt and occasional stains are removed with white spirit, gasoline or other solvent. Immediately before work, the dryness of the tree is checked, the surface is swept over with a clean cloth.
Preliminary application of antiseptics is required only if the soil is selected without their content.
Outdoor work is carried out in dry, no rain, preferably clear and warm weather.
The first primer layer is made liquid, as they say, “slightly thicker than water”, so that the composition is easily applied, distributed and impregnated without hindrance to the maximum depth of wood. Before use, the primer is thoroughly mixed with a spatula or wooden lath, achieving uniformity, if necessary, diluted with water or a solvent.
For uniform application to large-scale surfaces, it is more convenient to use a spray; foam rubber rollers, sponges or brushes can also be used. After complete drying, evaluate the result and decide whether a second primer is required. If in doubt, it is better to play it safe and apply another layer.
Despite the drying time of the soil indicated on the package, it will be more useful to wait an extra few hours and only then proceed to further painting so that the paint or varnish does not curl up and spoil the finished surface.
If all the rules are followed precisely, it will be possible to ensure excellent appearance and long-term operation of painted wood.