Surface Finishes

Surface finish is an important element in any specification or purchase order for stainless steel regardless of the intended end use. For those applications in which appearance is important, finish is a design element and must be specified. For those applications where finish is not so important, it should still be specified to avoid receiving a finish that is inappropriate for the application.

The purpose of this section is to help designers and specifiers achieve a better understanding of stainless steel finishes. The text describes and illustrates standard industry finishes and how finishes are applied to stainless steel.

Designers, specifiers and purchasing officials are also encouraged to contact ASSDA, a local stainless steel service centre or fabricator concerning any surface finish requirements.

Finish - A Design Element

There are several good reasons for paying close attention to the finish designation. In architecture or other highly visible applications, the appearance of stainless steel is a critical design element and a misunderstanding or the wrong finish can alter the desired effect. In consumer products such as appliances, cookware and automobiles, the gleam of well polished stainless steel has strong sales appeal. In commercial equipment, such as used in institutional kitchens, restaurants and hospitals, properly finished stainless steel helps to emphasise the feeling of cleanliness.

In addition to the visual appeal of polished stainless steel, there are a number of functionally important purposes served by properly prepared stainless steel surfaces. In sanitary applications, polished stainless steel not only looks clean, it is easy to clean and keep clean.

In aggressive environments, the smoother the surface, the better the corrosion resistance. A smooth surface is less susceptible to an accumulation of deposits which may become focal points for localised corrosion.

Finish and Fabrication

Some fabrication operations in manufacturing stainless steel products, such as deep drawing, may yield better results if the metal surface has a slightly rough texture to hold lubricants. Proper lubrication minimises tool wear, and it helps to reduce the severity of tool marks. In wire, the finish and coating serve to facilitate further steps in manufacturing such as cold heading of fasteners.

There are also economic considerations in specifying finish. For example, a cold rolled bright annealed finish might be specified instead of a more expensive No. 8 polished finish.

Relative comparison of grit size

FEPA - Federation of European Producers of Abrasives
CAMI - Coated Abrasive Manufacturers Institute (USA)