Preparatory treatment on iron and metal are of decisive importance for the durability.
In the treatments is referred to the following degrees of cleaning:
St is the abbreviation of steel brushing. All degrees assume that the surfaces have been cleaned of oil and grease and that very big rusting has been removed by rust knocking.
Light steel brushing. With a slight pressure the steel brush is moved to and from, so that all parts of the surface are brushed two times.
Thorough scraping with scraper of hard metal and steel brushing. The scraping must be made with a hard pressure, so that loose iron scale, rust and foreign bodies are removed. Then steel brush with heavy pressure. Loosened material is removed during the work, so that the effect can be controlled. Finally the surface is cleaned with vacuum-cleaner, clean and dry compressed air or clean brush. The surface must appear with a faint gloss.
Particularly thorough scraping with scraper of hard metal and steel brushing. The surface is treated as stated for St 2, but scraping and brushing is made first in one direction and then perpendicular to this. After cleaning as stated for St 2 the surface must appear with considerable gloss.
Sa is an abbreviation of sandblasting. Before sandblasting the surfaces must be cleaned of oil and grease, which is often forgotten. Very big rusting is removed by rust knocking.
Light sandblasting. The nozzle is moved quickly across the steel surface, so long that loose iron scale, rust and foreign bodies are removed.
Very thorough sandblasting. The nozzle is moved across the surface, until iron scale, rust and foreign bodies are removed to such an extent that remnants only appear as faint shadows. Finally should be cleaned with vacuum-cleaner, clean and dry compressed air or clean brush.
Sandblasting to metallic purity. The nozzle is moved across the surface, until all iron scale, rust and foreign bodies have been removed. Finally is cleaned as stated for Sa 2 ½. The surface must appear with uniform, light steel-grey colour.
It is essential that the cleaned metal is painted first time immediately after the cleaning, and that you prefer slowly drying priming paints applied by brush or airless spraying, where remnants of rust and iron scale appear. Treatment with paint roller or pressure spraying is unsuitable.
Well sandblasted or pure metal is protected effectively with quick-drying priming paint.