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"Mirror finish" -- is there a standard definition? [California] 

October 7, 2009

Is there an industry standard meaning to the term "mirror finish"?

John White
OEM Process Equipment Manufacturing Engineer - Santa Clara, CA, USA

Surface comparators display finishes that emulate mirrors from 4 microinches down normally produced by lapping.

Guillermo Marrufo
Monterrey, NL, Mexico

Short answer: No.
You can get a mirror finish on a relatively coarse uneven surface as well as a smooth surface. Normally it is suggested that an Rms/Rz be given as well as as an appearance designation in lieu of an acceptable finish part.

AF Kenton Nova Finishing Systems Inc. Huntingdon Valley, PA

There are two type of mirror finish on stainless steel.

1)No. 7 mirror finish is a directional mirror finish in which there are still visible polishing lines left on the surface.

2) No. 8 mirror finish is a "bathroom like" mirror finish where no polishing grit lines are visible.

www.ssina.com and www.nidi.org has free literature that describes these finishes.

Michael Liu Taylor    specialty stainless steel distributor Dallas, Texas