Basic Stainless Steel Plate Finish
There are eight basic stainless steel mill plate finishes available. Finishes 3, 4, 6, 7 and 8 are produced mechanically by using abrasive compositions and buffing wheels.
Unpolished No. 1. This is a very dull finish produced by hot-rolling the steel on hand sheet mills to specified
thicknesses, followed by annealing and descaling. The surface is microscopically very porous and uneven,
allowing a level of contamination pick-up that is many times its geometric surface area. Used in industrial
applications where resistance to heat or corrosion, not a smooth finish, is desired.
Unpolished No. 2D. This is a dull finish produced on hand sheet mills or continuous mills by cold rolling the
metal to the specified thickness, followed by annealing and descaling. The dull finish may result from the
descaling operations or may be developed by a final light cold roll pass on dull rolls. This finish is favorable to
the surface retention of lubricants in deep drawing operations, and it is generally used in forming deep drawn articles that may be polished after fabrication.
Unpolished No. 2B. This is a bright, cold-rolled finish produced similarly to the No. 2D finish, except the
annealed and descaled sheet receives a final light cold roll pass on polished rolls. The metal grains are
flattened, which facilitates removal of smearable contamination. However, the etched boundaries between
the grains are only partially sealed, resulting in a network of sub-surface crevices. Contaminants lodging in
these crevices are protected from contact with cleaning agents, leading to possible subsequent migration of
trapped contaminants onto the cleaned surface (bleeding). No. 2B is a general purpose finish used for all but
the most difficult deep-drawing applications, and it is more readily polished than No. 1 or No. 2D.
Polished No. 3. This is an intermediate polished finish for use where a semi-finished polished surface is
required for subsequent finishing operations following fabrication, or as a final finish with a 50 or 80 grit
abrasive compound. (In the case of metal sheets or articles that will not be subject to additional finishing and
polishing, a No. 4 finish is ideal.)
Polished No. 4. This is a general purpose mechanically polished stainless steel finish that is widely used for
architectural panels and trim as well as for restaurant, dairy and kitchen equipment. Initial grinding is
followed by coarser abrasives, with sheets eventually finished out with 100-150 mesh abrasives.
Polished No. 4 stainless steel still contains deep grooves and other
microscopic cavities that entrap and retain contaminants.
Buffed No. 6. A dull satin finish possessing low reflectivity, a Buffed No. 6 finish is produced with a greaseless
compound and 200-grit abrasive, and is top-dressed with chrome rouge.
Buffed No. 7. This very reflective finish is produced by buffing a surface that first was refined with 220-grit
abrasives to approximate a No. 6 finish. It is then buffed lightly with a white chrome rouge without removing
the satin finish lines.
Buffed No. 8. This is the most reflective mechanical finish. It is obtained by polishing with progressively finer
abrasives (320-grit and finer), followed by extensive buffing with very fine white chrome bar buffing
compounds. To the unaided eye, the surface appears free of grit lines from previous grinding operations.
Electropolished Surfaces. Electropolished surfaces are extremely smooth, macro-scopically flat,
microscopically featureless, and exhibit high high luster, reflectivity and brightness. Electropolishing process
substantially reduces the surface area available for contamination pick-up and eliminates all micro-cracks
and internal crevices
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