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Stainless Steel: Brushed Finishes


Last updated Dec 21, 2023 | Published on Jul 9, 2017

Used frequently for automotive and appliance applications, brushed mechanical finishes can heighten the aesthetic properties of stainless-steel components.

Boyd offers a wide variety of stainless-steel decorating capabilities including custom coatings, printed graphical images and patterns, and mechanical finishes. Of these options, one of the most popular metal decoration capabilities is adding a brushed mechanical finish. Brushed finishes distort the light reflection pattern on a part, and in turn can heighten visual contrast, increasing the perceived value of the part to which it is affixed.

What Are Brushed Mechanical Finishes?

Brushed metal finishes are produced by mechanically 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 brushing wheel. Brushed metal finishes for both stainless steel and aluminum can be linear or oscillating (overlapping).

Wet Number Four Stainless Steel Finish

Of the many options, the most common finish used is a wet number four polish. The uneven brush strokes of a number four polish/brush highlight the metal's brilliance on stainless steel without being too reflective. It provides a uniform look from the elongated brush pattern, and can withstand everyday wear by scuffing, scratching, and fingerprints. Common applications for a number four brush finish include automotive trim such as sill plates and arm rest trim, in addition to a number of home appliance uses.

Bright Annealed Stainless Steel Finish

By contrast, a BA (bright annealed) finish is a high-luster, brilliant chrome finish that is used frequently in the automotive industry for decorative parts. While various levels of reflectivity are achievable, the number eight BA finish is the most reflective. This finish is created by treating the surface with a series of fine abrasives, then buffing the surface to create a mirror like appearance. The buffing improves the corrosion resistance of the number eight finish, as it polishes away any minor surface imperfections where particles may stick and initiate the corrosion process. With its corrosion resistant properties, the number eight finish is commonly used for exterior applications requiring brilliant, highly reflective surfaces.

While these are two of the most popular options, this is far from a full list of metal finish options. Mechanical brush finishes can also be combined with a number of different colors, textures, and metals to add even more visual contrast to a part. To learn more about stainless steel options at Boyd, visit our blogs on Stainless Steel Alloys or Stainless Steel: Colors and Textures. To discuss your own custom metal finishing needs, reach out to our experts.

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