Primer is used everywhere to improve the quality of subsequent decorative painting and to protect the material from the negative effects of the environment. Each type of soil is used for each material, which ensures its full protection and increases the service life of the product. For a metal that is used almost everywhere due to its strength and durability, a corrosion-resistant primer is required.
This type of primer before applying the finish coating will provide the necessary protection against corrosion and rust, provide long service life and a presentable appearance of the product. If this processing step is neglected, then corrosion will begin to destroy metal surfaces, gradually penetrating deep into. Sometimes this process can go so far that the product becomes unusable and it is impossible to save it. All these troubles can be avoided by using anti-corrosion mixtures.
to contents ↑How to choose the right soil
A properly selected primer for metal from rust will protect and make metal buildings more durable, prevent the penetration of water to the surface, and increase resistance to corrosion.
All primer mixtures for this purpose differ in the ratio of ingredients of inorganic and organic origin and various mineral additives. As a rule, they are available in the form of concentrates or ready-made solutions. When purchasing a primer for rust, it is necessary to consider:
- A kind of metal (non-ferrous or black, alloy characteristics).
- Mechanical and climatic effects on the structure (humidity, mechanical stress, temperature extremes).
- Technical features of the anticorrosive mixture (the nature of the formation of a film on the surface, compatibility with the final paint coating).
- The drying time of the mixture. As a rule, acrylic quick-drying compounds are used for internal work, and alkyd ones with strong protection for external work. Both types of primers are easily applied to the surface, have a good degree of protection and dry relatively quickly.
Depending on the basis, they differ:
- water;
- oil;
- mixed.
In addition to the usual primers for metal, can be used:
- primer paints;
- soil varnishes;
- enamel primer.
They combine protective, improving adhesion and decorative functions. They are used both for self-staining and before applying the final topcoat.
When choosing the necessary soil mixture, it is also necessary to consider:
- scope (external or internal works);
- the presence of corrosion and rust on the iron, as well as the degree of damage;
- toxicity: highly toxic mixtures cannot be used for rooms, and when working with them on the street you must use protective equipment (gloves, glasses, a respirator);
- profitability: consumption per 1 m2 (usually about 100 g).
Various protective properties
The adhesion of the decorative paintwork to the surface and the durability of metal structures due to rust protection depend on the correctly selected properties of the soil mixtures. Depending on the properties, primers can be:
- Insulating, creating a dense film on the surface, which does not allow moisture and oxygen to penetrate the iron base, preventing the development of an oxidative process on it. Usually made on the basis of red whitewash. Great for outdoor use.
- Passivating soils transform the oxidizing properties of metal surfaces, slowing down the development of corrosion. They have enhanced protective properties. Thanks to the action of chemical modifiers, iron is protected even if the protective layer is broken and moisture gets on the metal base. This composition is good to use where metal structures are constantly in conditions of high humidity.
- Two-component phosphating. Suitable for all types of metals, made on the basis of phosphoric acid with the addition of active passivating components, can be epoxy and alkyd. They significantly reduce the subsequent consumption of paint or enamel, enhance their protective properties. Suitable for the treatment of galvanized steel, with which most paints do not have adhesion. The use of phosphating compounds provides, in addition to protection, a durable and uniform application of paint to the surface.
- Protectors. These primers are composed of the finest metal particles dissolved in the base of enamel or paint. When dried, they form a thin, durable film that reliably covers iron from any environmental influences. Metal structures that are constantly in the water, both in fresh and marine, protect perfectly.
- Soils with a rust converter are made on the basis of phosphoric acid, which, entering into a chemical reaction with iron oxide (rust), forms iron phosphate. Phosphates partially restore the product affected by corrosion, forming a strong protective film on its surface. Great for “rescuing” metal structures already susceptible to rust.
- Inhibitory primers not only provide a high degree of protection. When applied, they turn into another type of material - primer-enamel, combining the best properties of enamel and primer. These compounds, due to their wide range of applications, are gaining increasing popularity.
Primer Features
Protective primer works on metal products differ in some features from similar actions carried out on the surfaces of other materials. When priming metal substrates, it is necessary:
- Thoroughly clean the surface from rust and dust. For this purpose, you can use brushes and brushes with a metal pile. No cleaning is required if a rust primer is used. Applied on a rusty base, such a mixture, due to the action of the modifiers included in it, forms a reliable film that strengthens and protects the surface of iron.
- If staining is repeated, traces of old paint are removed. For best results, use a softener to remove old paint, to which, as a rule, various additives with anti-rust effect are added. The softener needs to be kept a little under a plastic film - after that the old enamel can be easily removed with a brush or spatula.
- To clear the surface cleared of old paint and rust to gloss and smoothness. On large metal structures, it is advisable to use grinding machines, small ones can be processed with sandpaper of various grain sizes.
- Thoroughly wash and dry the base prepared for priming.You can wash it with a car wash or just a soft cloth without lint. Small items are best washed under running water.
- The washed areas are well dried and, if possible, degreased. The use of degreasing solutions, such as gasoline, white spirit or other suitable composition for the subsequent applied soil will provide a more uniform distribution of the mixture, improve its protective qualities.
- If it is not possible to degrease a large area, then at least treat greasy spots. Neglect of this operation will lead to the fact that in places of greasy contamination, the composition will not provide strong adhesion to the base. Enamel, varnish or paint applied to such a surface as a topcoat will soon begin to peel off.
You can start applying the primer. For this purpose, use ready-made aerosol cans or do this using the following tools:
- Roller. Using various sizes of rollers for work, it is possible to quickly and economically process large areas.
- Brush. Suitable only for small items and for spreading hard-to-reach joints.
- Airbrush. Depending on the size and power, it can be used when processing very large areas.
The application of the first soil layer is carried out very thinly, in order to fill it with all microcracks and irregularities. Subsequent priming is carried out more abundantly.
The amount of applied primer layers varies depending on the purpose of the workpiece and its operating conditions. Metal structures are strong and durable under the conditions of their operation. Correctly selected protective primer-mixture with the effect of anti-rust will ensure high-quality subsequent application of paint, varnish or enamel, and will prevent the occurrence of corrosion for a long time.
