Raw Stainless Finishes
Wet painting, powder coating, and plating, as mentioned in our previous article, can create the desire appearance of a stainless steel part. Stainless steel can also be mechanically treated to create different appearances without further finishing. While there are dozens of different patterns, colors, and reflectivities, the four basic types are No. 2B, No. 3 and No. 4, No. 8, and BA. All of the types mentioned in this article are purchased straight from the stainless steel manufacturer.
No. 2B- Matte finish
No. 2B is the mill finish and requires no further processing. It has a dull, matte appearance. While not ideal for aesthetics, it is the least expensive finish. No. 2B is produced by cold rolling steel followed by descaling in an acid solution.
Applications:
- Chemical plant equipment
- Refrigeration
- Paper mill equipment
No. 3 and No. 4- Brushed finish
Both No. 3 and No. 4 are produced using abrasive belts. The belts form a pattern of fine parallel lines with muted luster. No. 3 finish uses 120-150 grit abrasive belts, and No. 4 uses 150-180 grit belts. Both finishes can vary with different suppliers and batches, so it may be helpful to request a sample to make sure the finish is as desired. Brushed finishes have strong decorative appeal, especially for architectural pieces as they are not too reflective. There is a slight reduction of corrosion resistance due to the grooves on the surface.
Applications:
- Jewelry
- Home appliances
- Architecture
No. 8- Mirror finish
No. 8 is a highly reflective finish. It is made by mechanically treated with a series of progressively finer abrasives. As a result, the smooth surface improves corrosion resistance.
Applications:
- Mirrors
- Ornamental trim
- Clean rooms
- Reflectors
BA- Bright annealed
Bright annealed stainless is similar in appearance to No. 8; however, it’s not quite as clear and defect free. BA steel is annealed under an atmosphere so that mill scale is not produced. The finished surface is highly reflective without further polishing or buffing.
Check out these common finishes as well as more rare finishes at The Stainless Steel Information Center.
Which to choose?
Some finishes are more aesthetically pleasing, while others are more practical. Finishes are not limited to this list, as there are countless others that may be more appropriate for your project. For example, we do glass-bead finishing in-house. Contact us and we’ll be happy to help with your next project.