On this page 10 sections
What is the difference between 2B, BA and No. 4 stainless finishes?
Short answer
2B is the standard cold-rolled, annealed and pickled finish, smooth and slightly reflective. BA (bright annealed) is mirror-like, annealed in a controlled atmosphere. No. 4 is a brushed finish with visible grain lines. No. 1 is the dull hot-rolled finish on plate.
Mill finishes
No.1: hot-rolled, annealed and pickled, dull and rough, for plate. 2D: cold-rolled and pickled, dull. 2B: cold-rolled, annealed, pickled and skin-passed, the standard sheet finish. BA: bright annealed, reflective.
Polished finishes
No.4: brushed with short grain lines, for kitchens and architecture. HL (hairline): long continuous lines. No.8: mirror polish, decorative.
Choosing
For process equipment, 2B is common. For hygienic surfaces, specify roughness (Ra) values. For coastal architecture, choose a smooth finish and SS 316.
Finish and corrosion
Smoother finishes hold fewer deposits, so they clean more easily and resist pitting better in mild chloride exposure. For coastal architecture and hygienic equipment, a smoother finish or electropolishing often matters as much as the grade.
Specifying roughness
Materials in this guide
Related guides, comparisons and articles
Frequently asked questions
Is BA finish more corrosion resistant than 2B?
Its smoother surface gives slightly better resistance to staining and pitting, but the grade matters more.
What is a hairline (HL) finish?
A long-grain brushed finish used for decorative panels and elevator interiors.
What is the smoothest standard finish?
No.8 (mirror). For process equipment, specify a maximum Ra value instead of a named finish.
Which standards define pipe, fitting and flange dimensions?
ASME B36.10M and B36.19M for pipe, ASME B16.9 and B16.11 for fittings, and ASME B16.5 and B16.47 for flanges. EN and IS equivalents are used on some projects.
Does Bright Tubes supply the materials in this guide?
Yes. SS 316 Stainless Steel and related products are supplied from stock or mill-sourced, with EN 10204 certificates.