What is pretreatment for powder coating?
Pretreatment means surface preparation for the powder coating to be applied to metals. Surface preparation includes:
Mechanical cleaning includes methods like DA Sanding and Sand Blasting. This abrasive action not only removes the surface
impurities but also eliminates scratches and surface irregularities. Cleaning is very good, however, coating must be done immediately because the cleaned surface is in a highly reactive state and corrosion occurs very soon.
Chemical cleaning includes removal of dirt, oil and grease, and the oxidation products present on the surface by means of chemicals. The chemicals may be applied by wiping, spraying or dipping. The nature of chemicals used depends upon the base metal and will be discussed later in detail.
Application of conversion coating. These are applied for three purposes:
- Provide temporary in-process corrosion protection before application of powder coating.
- Promote good adhesion of the powder coating to the substrate.
- Impart under-paint corrosion inhibitor to improve the life of the powder coating.
Note: The type of the conversion coating used depends upon the base metal and will be discussed later.