Before painting, galvanization supposed to grow old within 1-2 years. It is necessary for weathering under natural conditions zinc corrosion products and the formation of strong zinc patina. In addition, during aging are formed by the roughness, due to which the paint will stick better.
A galvanized sheet is often covered with mineral oil for protection during transportation and storage. Before painting, remove this oil with organic solvents, for example, a 5 percent solution of ammonia water. During the degreasing galvanizing as often as possible and change soiled instruments to securely remove the oil film.
Usual dirt that has accumulated on the coating can be washed off with detergent. Residues of solvent or detergent, remove with clean water under pressure. Wait until surface is dry.
If the surface of galvanized steel sheet is rust or old flaky paint, sand the damaged area to fine-grained sandpaper. You can also use a light sanding when the diameter of the abrasive 200500 microns. Be careful not to damage the thin zinc coating.
To paint was durable and reliable, galvanized sheet is first coated with primer. For economy it is better to choose a primer and paint close to the color of the shades – then it will be enough one coat of paint.
Alkyd primers are not recommended because resin included in the composition, interact with the oxides of zinc and collapse. The coloring for this reason it will be fragile and short-lived.
Choose a special paint for galvanized surfaces. On sale now a fairly wide range of imported and domestic paint products. Compare their characteristics, browse on the Internet customer reviews.