The term surface pretreatment or pretreatment summarises the steps that are made before covering with wet or powder paint. Normally these are cleaning and the installation of adhesion enhancing or corrosion protecting layers (conversion layers and primers). An insufficiently performed pretreatment can lead to craters in the varnish film.

Due to the mechanical pretreatment coarse contaminations such as rust or scale as well as bumps and ridges at edges are removed. Grinding, brushing and blasting are typically applied procedures in wet painting and powder coating. Degreasing occurs in the most cases with aqueous cleaners or solvents.

The choice of the suited pretreatment procedure for the application is determined by:

• Material and quality
• Surface condition
• Requirements for the surface pretreatment (aesthetics/functionality) and application area of the final product
• Economic and environmental considerations.