Mill finish
State the governing flat-product standard and exact finish designation.
Technical guide
Stainless Steel Surface Finish Chart
A finish designation identifies a production route or appearance family, but it does not by itself guarantee roughness, gloss, grain, color or defect acceptance.
Common referencesASTM and EN terminology
Appearance controlApproved sample plus viewing rules
Functional controlRa, lay, cleanability and defects
Decision summary
Specify both the finish route and the acceptance result
Mill finishes, mechanically polished finishes and electropolished surfaces require different controls. Translate the visual intent into measurable purchase-order language.
Brushed appearance
Define abrasive sequence, final grit reference, grain direction, color range and visible-face protection.
Reflective finish
Use a reference sample and agreed gloss, image clarity or defect criteria where appearance is critical.
Functional roughness
State the roughness parameter, cutoff, measurement direction, sampling and instrument method.
Hygienic service
Control weld finishing, crevices, cleanability, contamination and any sector-specific standard.
Electropolishing
Define the substrate preparation, required removal or result, acceptance tests and post-process cleaning.
Reference table
Common stainless steel finish designation chart
The cross-reference is an orientation aid based on worldstainless terminology. Exact appearance and roughness must be agreed separately.
| Process family | ASTM term | EN term | Practical procurement note |
|---|---|---|---|
| Hot rolled | No. 1 | 1E or 1D | Confirm descaling route, thickness and surface acceptance |
| Cold rolled, dull | 2D | 2D | Low-reflectivity mill finish; agree visual limits |
| Cold rolled, smooth | 2B | 2B | Common smooth mill finish; roughness is not fixed by the name alone |
| Bright annealed | BA | 2R | Bright surface depends on alloy, gauge and annealing route |
| Brushed or polished | No. 4 | 1J or 2J | Specify abrasive, grain direction and approved sample |
| Satin polished | No. 6 | 1K or 2K | Define the supplier process and appearance standard |
| Mirror polished | No. 8 | 1P or 2P | Agree reflectivity, image quality and defect limits |
| Electropolished | No direct common code | No direct common code | Specify substrate finish, process and acceptance tests |
Designation mapping is not an automatic equivalence certificate. Standards, producer routes and commercial finish names may differ.
Working method
Turn an appearance word into an inspection clause
Words such as satin, brushed and mirror are subjective until the order defines how and where the surface will be judged.
Name the base finish
State ASTM, EN or another controlling finish designation and the applicable product standard.
Add measurable properties
Define Ra or another parameter, lay direction, gloss or reflectance only where relevant and with a test method.
Control visual inspection
Use an approved sample, lighting, viewing distance, direction, visible faces and allowable defect limits.
Protect the delivered surface
Specify film type, laser compatibility, handling, weld restoration, cleaning, packaging and traceability.
Limits and escalation
Avoid finish shorthand that creates disputes
Grit is not roughness
The same nominal abrasive grit can produce different Ra values on different machines and substrates.
2B is not one appearance
Alloy, thickness, rolling route and supplier can change color and reflectivity within the designation.
Ra is not the whole surface
Roughness alone does not define waviness, lay, gloss, pits, scratches or cleanability.
Samples need control
Identify the approved sample, viewing conditions and acceptable production variation.
Interactive planning aid
Translate finish intent into RFQ inputs
Choose the primary finish intent to see the minimum controls a supplier needs.
Frequently asked questions
Stainless steel surface finish FAQ
2B is a smooth cold-rolled mill finish. No. 4 is a mechanically polished directional finish whose final appearance depends on the abrasive process and acceptance standard.
No. A finish name or grit reference does not guarantee one roughness value. State the required parameter, method, direction and sampling if roughness matters.
No. Bright annealed is a bright mill finish, while mirror finishes typically involve additional polishing and stricter visual controls.
Define visible faces, lighting, distance, viewing angle, approved sample, allowed defect size or density and protective handling.
Method, sources and review
Traceable sources and review status
Industry overview and common ASTM and EN finish terminology.
Illustrated industry guide to architectural and mill finishes.
Technical education on finish processes, terminology and specification.
Official general requirements for stainless plate, sheet and strip, including finish terminology.
Finish terminology is a starting point. The contract should control the applicable standard, reference sample, measurement method, visible faces, defect limits and protective handling.
Surface finish context
Name the finish with the form, directionality and acceptance basis.
A finish chart provides a common language, but the delivery condition must also state the product form, roughness or appearance criteria, protective film and inspection method.
- Finish designation
- Appearance criteria
- Inspection method
Visual process context
Use visuals to distinguish process appearance from final acceptance.
Use one image for the production or finishing route and another for the approved surface appearance or inspection sample.
Engineering and sourcing support
Request stainless with a finish suppliers can verify
Send grade, product form, finish code, roughness or sample criteria, visible faces, film, inspection, quantity and destination.