We get quite a few inquiries here at Monarch for satin finish aluminum angle. The trouble is that a “Satin” finish means different things to different people.
According to the Metal Finishes Manual put out by the National Association of Architectural Metal Manufacturers, they define a Satin Finish as a mechanical finish applied by wheel or belt polishing with grits of varying degrees of fineness. Typically we are applying this finish to 6063 Sharp Corner aluminum angle and applying a brushed finish to the outside face(s) of the angle to match other interior elements. We can do this with a coarse 120 Grit Grain, which we would call a #4 finish. We can also apply a smoother grain with a higher grit belt, which we would call a #6 finish, which would be a 180 to 220 grit. You can feel the difference by running your finger over the material and seeing if you can feel the grain.
The confusion arises because customers will also use a “satin” finish to mean a clear satin anodized finish (anodized aluminum angle). This is anodic treatment of the aluminum that forms a durable oxide coating on the surface of the aluminum. This anodic coating does not affect the surface texture of the aluminum, but provides increased resistance to corrosion as well as resistance to abrasion. Aluminum can be anodized in different colors, but the most common is clear anodized. Another choice in anodized aluminum is whether the part needs a thicker oxide film for outdoor use (such as a 204 coating) or whether a thinner oxide layer would suffice (a 201 coating). If you are drilling, punching or cutting your anodized material, then the material will not be protected from the elements at the cuts.