• No. 0: Hot rolled, annealed, thicker plates
• No. 1: Hot rolled, annealed and passivated
• No. 2D: Cold rolled, annealed, pickled and passivated
• No. 2B: Same as above with additional pass-through highly polished rollers
• No. 2BA: Bright annealed (BA or 2R) same as above then bright annealed under oxygen-free atmospheric conditions
• No. 3: Coarse abrasive finish applied mechanically
• No. 4: Brushed finish
• No. 5: Satin finish
• No. 6: Matte finish
• No. 7: Reflective finish
• No. 8: Mirror finish

Mechanical finish designations

#3 Finish

Also known as grinding, roughing or rough grinding. These finishes are coarse in nature and usually are a preliminary finish applied before manufacturing. An example would be grinding gates off of castings, deburring or removing excess weld material. It is coarse in appearance and applied by using 36–100 grit abrasive.

When the finish is specified as #3, the material is polished to a uniform 60–80 grit.

#4 Architectural finish

Also known as brushed, directional or satin finish. A #4 architectural finish is characterized by fine polishing grit lines that are uniform and directional in appearance. It is produced by polishing the metal with a 120–180 grit belt or wheel finish and then softened with an 80–120 grit greaseless compound or a medium non woven abrasive belt or pad.

#4-5 Dairy or sanitary finish

This finish is commonly used for the medical and food industry and almost exclusively used on stainless steel. This finish is much finer than a #4 architectural finish. Great care should be taken in removing the surface defects in the metal, like pits, that could allow bacteria to grow. A #4 dairy or sanitary finish is produced by polishing with a 180–240 grit belt or wheel finish softened with 120–240 grit greaseless compound or a fine non woven abrasive belt or pad.

#6 Finish

Also known as a fine satin finish. This finish is produced by polishing with a 220–280 grit belt or wheel softened with a 220–230 greaseless compound or very fine non woven abrasive belt or pad. Polishing lines should be soft and less reflective than a #4 architectural finish.

#7 Finish

A #7 finish is produced by polishing with a 280–320 belt or wheel and sisal buffing with a cut and color compound. This is a semi-bright finish that will still have some polishing lines but they should be very dull. Carbon steel and iron are commonly polished to a #7 finish before chrome plating. A #7 finish can be made bright by color buffing with coloring compound and a cotton buff. This is a good way to keep polishing costs down when a part needs to be shiny but not flawless.

#8 Finish

Also known as a mirror finish. This finish is produced by polishing with at least a 320 grit belt or wheel finish. Care should be taken in making sure all surface defects are removed. The part is sisal buffed and then color buffed to achieve a mirror finish. The quality of this finish is dependent on the quality of the metal being polished. Some alloys of steel and aluminum cannot be brought to a mirror finish. Castings that have slag or pits will also be difficult, if not impossible, to polish to a #8. 

    To achive these types of finishes is not an easy procress and usually requires someone with years of experiance in this craft with a skilled hand and trained eye, and good knowledge about the metal. So, if you are looking for one of these finishes, Contact Us, we would be glad to help, because Walsdorf is Your Metal Fabrication Specialist.