Surface preparation

For any given paint system, surface preparation is the single important factor which would determine its performance or the performance of any coating is directly dependent upon the correct and thorough preparation of the surface prior to coating.

The most expensive and technologically advanced coating system will fail if the surface preparation is incorrect or incomplete.

Surface preparation can be broken down into two main categories.

• Surface Profile
• Surface Cleanliness

Surface profile or Anchor Pattern

Is the determination of the roughness of the surface and for painting purposes involves depth of the profile, peak density and angularity of the profile.

Most paint systems require an Surface profile characterized by a surface roughness and a roughness profile to obtain proper adhesion.

Surface Cleanliness

Involves determining how much of the original mill scale, rust and paint have been removed from the surface as well as how much invisible surface contamination is present usually in the form of salts.

Every joint shall be inspected for surface cleanliness. The surface shall be cleaned to achieve a minimum surface cleanliness of Sa 2½. Surface that do not comply with the requirements shall be rejected and cleaned again and the surface shall remain at Sa 2½ until application of coating.