Anti-corrosion protection

Corrosion is the process of material destruction due to external factors. Destructive factors include proximity to seawater or freshwater, the presence of chlorides or sulfur compounds in the environment, or simply atmospheric conditions. The product of the corrosion process is rust, a coating that forms on the metal.

Corrosivity categories are used to define the degree of corrosiveness. According to the PN EN ISO 12944-2 standard, this corrosiveness is classified into six levels for the atmosphere and three levels for water and soil. To properly select a painting system, it is necessary to determine the conditions in which the structure will operate, and therefore determine the environmental corrosivity category. These categories are as follows: C1 - very low degree of corrosive aggressiveness, internal structure in a heated room with a clean atmosphere (example: shops, offices, school) C2 - low degree of corrosive aggressiveness, external structure in a rural environment or internal structure in an unheated room where condensation may occur (example: warehouses, sports halls) C3 - medium degree of corrosive aggressiveness, external urban or industrial environment, internal environment with high humidity and air pollution (example: breweries, laundries, dairies) C4 - high degree of corrosive aggressiveness, external industrial environment, coastal areas with medium salinity, internal environment such as chemical plants, swimming pools, repair shipyards C5-I - very high degree of corrosive aggressiveness (industrial) - external environment with high humidity and aggressive atmosphere, and internal environment with almost constant condensation and high pollution C5-M - very high degree of corrosive aggressiveness (coastal) - areas coastal, distant from the shore After appropriate selection of the environmental corrosivity class and determining the minimum required durability of the painting, the appropriate thickness of the paint coating can be selected and the theoretical yield of the product can be determined.

Two-component polyurethane paints are the most durable. They provide excellent protection against corrosion and UV radiation. Application of these paints is more difficult due to the need to combine the two components and mix them thoroughly. These products should typically be applied at temperatures above 10°C. One such product is the Telpur S210 primer-finish . It is available in 2, 2, and 10 kg packages in RAL colors. If a small amount of paint is needed, the Lowigraf-Pur two-component primer-finish . It is available in 0.88 l and 2.75 l packages in a limited color range. In highly corrosive environments (e.g., if the fence is located next to a busy road or a sidewalk that is salted in winter), we recommend applying an epoxy primer before applying the polyurethane paint. This can be FEG-C or Telpox P 100 . If we want a simple and quick application, we can choose single-component products, for example Stal-Kor rust primer or Lowigraf polyvinyl paints.

There's no need to wash off the rust remover. Depending on the product chosen, you simply need to wait a specific time before applying subsequent coats: If using Top-Kor , wait 12 hours. Top-Kor can only be repainted with solvent-based paints. If using Neodur Metalforce , wait 24 hours. Neodur Metalfroce can be repainted with both solvent-based and water-based paints. When applied to rusted iron surfaces, the rust remover will create a very stable, graphite-gray/black layer that will resist further oxidation. When applied to smooth, non-rusted steel, it will create a colorless varnish coat with good adhesion to the substrate, blocking out moisture and oxygen from the air and temporarily protecting the substrate from corrosion.

Not all paints can be applied to a freshly galvanized surface. Galvanized surfaces should be seasoned for approximately six months. If repainting is necessary, the structure should be washed with an ammonia solution before painting.

To properly prepare the structure for painting, first of all, the surface must be mechanically cleaned (removing old, flaking coatings and loose rust) and degreased. Emulsol RN-1 surface degreaser can be used for this purpose. This highly efficient product, which, when prepared at a 2-3% solution (0.5 liters in approximately 16-25 liters of water), is sufficient to clean 20 to 50 m², depending on the degree of contamination. If the surface has rust that cannot be removed mechanically, it is best to use a rust remover. If the surface will be repainted with solvent-based paints, Top-Kor , which is applied by brush, roller, or spray. One liter of the product is sufficient to protect approximately 10 m². Wait 12 hours before applying subsequent coats. Another product for removing rust from surfaces is Neodur Metalforce , which can be used under both solvent-based and water-based paints. After applying the product, wait 24 hours before applying subsequent coats. Depending on the topcoat used and the substrate, it may be necessary to prime the surface with an anti-corrosion primer.

Drying times vary depending on the product and are individual. Substrate and ambient temperature, as well as air humidity, are key factors influencing drying time. For most single-component products, a general rule can be applied: solvent-based products dry faster than water-based ones. This is because the solvent is more volatile and evaporates from the surface faster than water. Example drying times for single-component paints: Lowicin (solvent-based polyvinyl paint for galvanized roofs) - 2-3 hours; eko-Lowicyn (water-based acrylic paint for galvanized roofs) - 12 hours; Telkyd S 200 TM (solvent-based polyvinyl primer-finish) - dust-free after just 20 minutes. Two-component products (epoxies or polyurethanes) typically have longer drying times because, in addition to physical drying, a chemical reaction occurs between the base and the paint hardener. Drying times for two-component paints (colloquially speaking, when they stop sticking) are 0.5-3 hours, depending on the product. However, it's important to remember that this doesn't mean the structure can be transported or repainted after that time. Example drying times for two-component paints: Telpur T 300 matt - dry to touch 0.5-1 hour - repainting after 24 hours Telpox T 300 - dry to touch 1-4 hours - repainting after 24 hours Telpox P 100 - dry to touch 0.5-2 hours - repainting after 24 hours There are cases where a long drying time is an advantage. For example, when spray painting with high-gloss paints, a longer drying time will work to our advantage. During spray painting, so-called paint mist is created, which, as it settles, should blend into the paint layer already applied to the substrate. If the paint dries too quickly, the falling particles won't be able to bond with it, creating an unsightly "dust"—tiny dots. This is why Telpur T 300 (gloss version) has a longer drying time. If a short drying time is important, consider products that allow for a wet-on-wet second coat, such as Telkyd S 200 TM or Telpur S 210 .