Williams Metal Finishing

Williams Metalfinishing Types of Finishes

The information provided below is somewhat subjective and is used as our general guide at Williams Metalfinishing.

#3 Finish - Grain finish. Also called Grinding, Roughing or Rough Grinding
Very coarse finish. The material is polished to a uniform finish between 60 and 80 grit.

#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 120 - 180 grit belt or wheel finish.

#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.

#6 Finish
Fine grain. This finish is produced by polishing with a 220 - 280 grit belt.

#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. 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 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 is dependent 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 Trizact
30   250  
40   200  
60 145 150  
80 71 125  
100 61 69  
120 52 58 A160
150 42 47 A130
180 30 34 A110
220 20 22 A90
240 15 17 A65
320 12 14 A45
500+ <3 <3 A35
1200     A20
1500     A10

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