Zinc primer is used to provide tread protection of metal from corrosion, rust, and also after mechanical damage to the coating. It is 70-90% zinc-filled, that is, it contains this amount of zinc dust from the total mass of substances. However, due to such a large amount of zinc, the coating itself is prone to defects.
Manufacturers puzzled over how to make the material more resistant to external influences, as well as reduce the zinc content. The most optimal solution was the use of zinc pigments of various structures: flakes and dust. The primer formulation was brought to the ideal: 25% zinc content plus improved protective properties.
to contents ↑Composition of Substances
Zinc-filled primer may contain dust or a mixture of dust and flakes as the main substance. Among other components of the composition of the primers for metal can be identified:
- inhibitors - give the material anti-corrosion properties, increase adhesion (for galvanized iron - this is especially important);
- phosphates on aqueous solvents - interact well with any type of top coat;
- chromic acid salts - change the properties of the metal, make it passive to the formation of rust;
- iron minium - is used as a neutral pigment that can form a moisture-resistant insulating film on the surface;
- surfactants - a converter of rust into sparingly soluble or rapidly degradable compounds;
- powders of other metals (mono-, bi- and combined mixtures) - the higher the content, the higher the anticorrosion properties of the primer;
- solvents;
- desiccant;
- resins;
- hardeners, etc.
Based on the composition of the substances, the type, quality, properties and purpose of the primer materials for different types of metal are determined. “Pure zinc” primer mixtures belonging to the category of tread, contain more than 90% zinc. The rest is filled with special resins, water glass, and so on.
Primers usually have less pigment in their composition, so they are practically not used as a topcoat.
Specifications
Among zinc primers, converter and protectors are valued. Although you should not underestimate other types of primers for metal. When used appropriately, the protective functions will be justified.
Of the general characteristics, we note:
- anticorrosive protection of iron (galvanized and not galvanized);
- rust protection (many primers can be applied directly on top of rust, like a converter);
- increased adhesion of the base and topcoat;
- water tightness;
- durability (some types of primers for metal have a service life of up to 50 years, on average - 15-25 years);
- high strength, resistance to mechanical stress, various types of physical activity;
- chemical inertness to almost all types of substances;
- heat resistance;
- fire resistance;
- resistance to the influence of biological environments;
- resistance to UV radiation.
Appointment
It has already been repeatedly mentioned that zinc-containing primers are effectively used to treat any surface made of iron. Metal structures, tanks, systems outside and inside the premises for domestic, economic, public and industrial use. In conditions of constant influence of moisture, a rust converter and an iron tread against corrosion are especially important.
The primer can be applied with a brush, roller, spray method (a feature of the aerosol type of packaging). The treated surface should be pre-cleaned, degreased, dried, repaired, polished. During operation, it is important to observe the following rules:
- before use, mix the mixture thoroughly (shake);
- adhere to the norms of permissible operating temperature (depending on the type of zinc-containing primer, indicators range from +5 to +40 degrees Celsius);
- a primer is applied in at least 1-2 layers, a break is required between applications.
Experts advise not to rely on the converter or combined compositions of the "three in one" type (converter - protection - decorative layer). The presence of defects in the iron surface reduces the operational life of the structure itself, however effective the further protection is.
