The information provided below is somewhat subjective and is used as our general guide at Williams Metalfinishing.
#4 Non-Directional Angel Hair
#4 Architectural Finish – Also called 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 80- 180 grit belt or wheel finish. (65 RA – 30 RA)
#4 Dairy or Sanitary Finish
This finish is commonly used for the medical and food industry – almost exclusively used on stainless steel. Great care should be taken in removing the surface defects in the metal – like pits – that could allow bacteria to grow. This finish is produced by polishing with a 180 – 240 grit belt. (30 RA – 20 RA)
Fine grain. This finish is produced by polishing with a 180 – 280 grit belt. (20 RA – 12 RA)
Smooth buffed finish with a very bright appearance. Light haze. The part is belt polished with a 280 – 320 belt then buffed with a cut and color compound. This is a common finish in preparation for chrome plating, powder coating, anodizing, etc. This is a good way to keep polishing costs down when a part needs to be shiny but not flawless.
#8 Mirror Finish
“Mirror” bright finishes with clear reflection – Very light haze. All surface defects are removed. The part is buffed and then color buffed to achieve a mirror finish. The quality of this finish can depend on the quality of the metal being polished. Castings that have pits will be difficult – if not impossible polish to a #8.
True #8 Mirror Finish
Finish Cross Reference Chart