Williams Metalfinishing Types of Finishes

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)

#6 Finish
Fine grain. This finish is produced by polishing with a 180 – 280 grit belt. (20 RA – 12 RA)

#7 Finish
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
No haze.

Finish Cross Reference Chart

Grit RA RMS
30   250
40   200
60 145 150
80 71 125
100 61 69
120 52 58
150 42 47
180 30 34
220 20 22
240 15 17
320 12 14
500+ <3 <3
1200    
1500