Surface codes cause a lot of confusion in purchasing. The common definitions:

• 2B: cold rolled + annealed + pickled + skin passed. Relatively flat with a slight grey tone; the most common general-purpose finish for stamping, bending and welded parts. • BA (bright annealed): annealed in a protective atmosphere, bright and with low Ra. Used for kitchenware, decorative parts and parts to be plated or polished — but BA is not a mirror finish. • No.4: brushed with roughly 120–150 grit abrasive, producing short directional lines; common on elevator panels, kitchen equipment and architectural trim. Grain direction matters — keep the same direction within one batch.

Guidance:

1) Corrosion only: 2B and BA behave similarly for the same grade; the real drivers are contamination, scratches and free iron on the surface. 2) Appearance: decorative parts favour No.4 or BA; protect the surface during transport. 3) Welding: 2B is the common choice; pickle and passivate after welding to restore corrosion resistance.

Specify both the finish code and the grain direction on the purchase order to avoid disputes at inspection.