Stainless steel

Surface preparation

Corrosion resistance

Stainless steels are used for their corrosion resistance in a wide variety of service environments, usually without additional coatings. In certain circumstances, however, stainless steel components or structures may require a coated (paint) finish.

Coating systems for stainless steels must be carefully selected to provide sufficient durability to meet the requirements of the service environment and its associated operating conditions. The combination of surface steel preparation and formulation of the paint system are key factors in meeting these objectives. In certain environments, localised breakdown of the coating can lead to corrosion. This may be more severe than that experienced with un-coated surfaces and may result in high, localised, rates of attack.

Flatter and smoother surface

In general, stainless steels have flatter and smoother surfaces than carbon steels. This applies particularly to thin cold-rolled products (sheet and coil) and may adversely affect adhesion between the metal surface and the coating system. Roughening of stainless steel surfaces prior to coating is essential. This can usually be achieved by MontiPower® instead of loose abrasive blasting, light hand abrasion or chemical etching. Compared to loose abrasive blasting you can be sure of no need for loose iron free media such as alumina or silicon carbide to avoid contamination, which can result in rust staining on the surface prior to coating. With a pneumatic, cordless or electric Bristle Blaster® stainless steel belt solution surfaces can easily be prepared to give a surface roughness Ra of minimally 50 micron and a minimum cleanliness of grade 2 in accordance with BS 7079:Part 1A. MBX® offers finer roughness of Ra approximately 10-30 micron.