- Separate 2B, 2R/BA and mechanically brushed/polished finishes.
- Grit is not a universal appearance standard; pair it with Ra and a master.
- Control grain through nesting, forming, welding and assembly.
- Heat-tint removal, passivation, contamination control and packing all matter.
Values in this guide are practical starting points for RFQ, DFM and prototype validation. They do not replace load calculations, regulations, material certificates, qualified procedures or approved production drawings.
Separate Mill Finish from Mechanical Finish
Common sheet finishes include 2B, a smooth matte cold-rolled/annealed/pickled/skin-passed surface; 2R/BA, a brighter annealed reflective finish; and mechanically finished 2J/2K/No.4-type appearances. Names do not map perfectly across standards. State material standard, finish designation, one- or two-side treatment, film and cosmetic face—not just “brushed stainless.”
Grit Number Is Not a Universal Appearance Standard
FEPA, CAMI, JIS and abrasive products differ, so “240 grit” can produce visibly different grain. A stronger specification combines an approved sample, abrasive/process record, Ra range and grain direction. Decorative brushing may begin discussion around Ra 0.4–1.2 μm, but hygienic, food, optical and premium cosmetic work requires dedicated validation rather than this generic range.
Control Grain Through Nesting and Assembly
Draw a grain arrow on every visible face and show the visual direction after forming. Adjacent doors, frames and covers with different grain orientations appear mismatched under one light. Fixed-direction nesting reduces material yield and should be priced early. Mirrored left/right parts cannot always be rotated in nesting without reversing visible grain.
Blend Welds Without Destroying Geometry
Control weld size and heat input before staged blending. Excess grinding thins the parent material, washes out edges and creates shiny patches. Define whether corners retain a crisp line, the blend radius and grain continuity. Approve a welded-and-brushed process sample for critical cosmetic work, not only a flat coupon.
Restore Corrosion Resistance After Fabrication
Weld heat tint indicates a damaged passive surface, with darker tint generally representing greater chromium depletion. Use suitable mechanical cleaning, pickling and passivation as required and rinse thoroughly. Passivation removes free iron and supports passive-film recovery; it does not automatically remove heavy oxide scale. Dedicate abrasives, brushes and protected benches to prevent embedded carbon-steel contamination and later rust staining.
Inspect and Pack the Finish Properly
Under controlled lighting, distance and angle, inspect grain, shade, scratches, blend transitions and weld areas. Measure roughness consistently—commonly across the grain—with a defined cutoff, and compare visually to the master. Protective film must suit forming/laser work and shipping duration; prolonged sunlight can leave adhesive. Use clean, nonabrasive, sulfur-free separators and keep tape/straps off A-surfaces.
REFERENCES
EN 10088-2 and ASTM A480/A480M (stainless sheet and surface finishes), plus ASTM A967/A967M (chemical passivation); use the contract-specified latest editions and approved samples.