There are a number of basic types of stainless steel finishes. Here’s a brief round-up of 10 Types of Stainless Steel Surface Finishes:
No. 1 Finish – Has a dull, rough, uneven appearance. Surface imperfections are sometimes erased by grinding, which can leave behind shiny spots. This finish is mainly used for industrial applications such as furnace arch supports, furnace conveyors, furnace linings, air heaters, boiler baffles, incinerators, kiln liners and industrial oven liners, among many others.
No. 2B Finish – Similar to 2D (see below) but has a comparatively shinier finish, often compared to a cloudy mirror. 2B can be more easily polished to a high luster than a No. 1 or No. 2 finish. It’s often used for everything from flatware, bakeware, and pharmaceutical equipment to plumbing fixtures, sheet metal products and solar collector panels.
No. 2D Finish – A dull silver or gray uniform finish which is applied to thinner coils. It’s preferred for deep drawing components since it retains lubricants well. Often used as a substrate since it holds paint well. Applications include roofing, petrochemical equipment and electric range parts.
Bright Annealed (BA or 2BA) – Produced by annealing (heat-treating), it is shiny and mirror-like but contains smudges or cloudy imperfections. Often used when a very reflective surface is needed. Applications include surgical instruments, fishing equipment, cookware, automobile trim, chute liners and textile finishing equipment.
No. 3 Finish – Moderately reflective, this finish features short, somewhat coarse parallel polishing lines that uniformly extend over the length of the coil. It’s often used in kitchen equipment, brewery equipment, scientific apparatus and food processing machinery.
No. 4 Finish – Similar to No. 3, this finish has short, parallel polishing lines that travel the length of the coil, but is more polished and reflective. Applications are varied, including dairy equipment, furniture, beverage equipment, sinks, water fountains, elevator doors and interiors, bus shelters and boat fittings.
No. 6 Finish – Less reflective than No. 4 Finish, it’s a dull silver-white with short linear polishing lines. While there are finishes currently being sold as No. 6, it is essentially no longer made. This finish was used in architecture from around 1930 into the 1980s. It can be seen on the panels adjoining the windows of the Empire State Building.
No. 7 Finish – Very reflective to the point of being mirror-like. Fine polishing lines are visible from a distance of several feet. Used in wall panels, ornamental trim and column covers.
No. 8 Finish – Quite mirrorlike, although not perfectly so, this finish is the most reflective covered by ASTM standards. Used for press plates, signage, wall panels column covers and mirrors.
TR (Temper Rolled) Finish – This finish is called for when strong mechanical properties are needed. Temper rolling is usually performed on polished rolls and the end result is an even, selective finish.