Unpolished or Rolled Finishes:

No. 1 A rough, dull surface, which results from hot rolling to the specified thickness followed by annealing and de-scaling.

No. 2D A dull finish which results from cold rolling followed by annealing and de-scaling, A 2D finish is used where appearance is of no concern.

No. 2B A bright, cold-rolled finish resulting in the same manner as No. 2 D finish, except that the annealed and de-scaled sheet receives a final light roll pass through
polished rolls. This is the general-purpose cold-rolled finish.


Polished Finishes:

No. 3 An intermediate polished surface obtained by finishing with a 100-grit abrasive. Generally used where a semi-finished polished surface is required. A No. 3 finish usually receives additional polishing during fabrication.

No. 4 A polished surface obtained by finishing with a 120-150 mesh abrasive, following initial grinding with coarser abrasives. This is a general-purpose bright finish with a visible “grain” which prevents mirror reflection.

No. 6 A dull satin finish having lower reflectivity than No. 4 finish. It is produced by Tampico brushing the No. 4 finish in a medium of abrasive and oil. It is used for architectural application and ornamentation where a high luster is undesirable, and to contrast with brighter finishes.

No. 7 A highly reflective finish that is obtained by buffing finely ground surfaces but not to the extent of completely removing the “grit” lines. It is used chiefly for architectural ornamental purposes.

No. 8 The most reflective surface, which is obtained by polishing with successively finer abrasives and buffing extensively until all grit lines from preliminary grinding operations are removed. It is used for applications such as mirrors or reflectors.

Notes:
Duct and fittings are normally fabricated from good formability 300 grade.

Fasteners are fabricated from a harder 400 grade, which is magnetic.