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Rich Smylie, GMN
By Richard Smylie | Jun 9, 2017
Brushed finish on a stainless steel sill plate

GM Nameplate (GMN) offers vast stainless steel and aluminum decorating capabilities including, custom coatings, graphic printed images/patterns and mechanical finishing. In part two of our series regarding stainless steel, we will discuss the options available when choosing a brushed finish on stainless steel. Brushed finishes distort the light reflection pattern and in doing so can increase the perceived value of a part to which it is affixed.

Brushed metal finishes are produced by polishing or wearing away the outer surface of the metal. Brush finishes can be applied overall or selectively, in one or multiple directions. To create a selective mechanical brush or a spun finish, a screen printed resist ink is applied to the metals’ surface prior to it being subjected to the mechanical brushing wheel. In doing so, the area protected by the resist ink will maintain its original brilliance, as it will not come in contact with the mechanical brushing wheel.

Brushed metals finishes for both stainless steel and aluminum can be linear or oscillating (overlapping). Brushed stainless steel finishes are particularly prevalent in the home appliance and automotive industries. The most common finish call-offs for stainless steel are BA for bright finish applications and No.4 for brushed.

A BA (bright annealed) finish is a high luster brilliant chrome finish that is frequently employed in the automotive industry. A  No. 8 BA finish is the most reflective finish call-off. This finish is created by treating the surface with a series of fine abrasives, and then buffing to create a mirror like appearance. The buffing finish improves the corrosion resistance of the No. 8 finish because it polishes away any minor surface imperfections where particles may stick and initiate the corrosion process. With this corrosion resistant property, the No. 8 finish is commonly used for exterior application requiring brilliant highly reflective surfaces.

A No. 4 brush finish is commonly employed by the appliance industry for applications that include ranges, washers, dryers, and refrigerator trim. The appeal of the No. 4 brush is the uniformity, and the highs and lows of the elongated brush pattern.

Brush patterns, when combined with colors and/or textures; add even more contrast to the aesthetics of the part. The next blog in our stainless steel mechanical finishes series will cover colors and textures.

For more information, check out our previous blog on stainless steel alloys