The appearance of red wires under the coating film is called filiform corrosion.
Rust points (spots) that penetrate the coating film under the coating film are called scarring corrosion.
The rust stains on the coating surface along the gap of the overlapping structure of the workpiece are called dripping yellow water.
1) Moisture passes through the cracks, pores or bruised parts of the paint film to the surface of the steel plate.
2) The rust cannot be effectively removed before painting, and special attention should be paid to the spots with rust and bean scars and spot welding gaps.
3) The steel surface is polluted before painting, such as fingerprints, water stains left to dry on the surface, and paint cannot be painted in time after surface treatment.
4) The coating is incomplete, with pinholes, missing coatings and other defects. If there are some gaps and spot welds that are not coated with paint, and if they are not sealed, yellow rust will easily flow.
5) The corrosion resistance of the coating used is poor.
6) The use environment is poor, such as high temperature, high humidity, and corrosion by corrosive media (acid, alkali, salt, etc.).
7) After the iron is exposed on the repaired part, the anti-rust primer is not sprayed, and the topcoat is sprayed directly.
Note: Some scarring corrosion and rust swelling under the coating film are caused by poor corrosion protection on the back of the steel plate and rust.
1) The surface to be painted must be cleaned to remove all rust, and paint with rust is never allowed. Paint should be painted in time after surface treatment before painting to prevent secondary pollution or rust.
2) Ferrous metal parts should be phosphating before primer coating, and should have good compatibility with the coating used.
3) The integrity of the coating shall be ensured and all surfaces of the bodywork including welds shall be coated with the coating.
4) Select coatings with excellent corrosion resistance and moisture resistance according to the use environment of the coated object, such as cathodic electrophoretic coatings, epoxy powder coatings, etc.
Remove exposed steel, sand the affected area to a clean, shiny surface, and repaint it.
南北潮商城 - 《www.nbchao.com》