Stainless Steel Surface Finish
No. 3 Stainless Steel Finish
Specifications, Supply & Technical Guide
No. 3 stainless steel finish is an intermediate polished surface with visible linear polishing lines. It is coarser than a general-purpose No. 4 polished finish and can be used as a final industrial / decorative finish or as an intermediate surface before finer polishing. For procurement, define the substrate grade, abrasive route, grain direction, Ra / Rz requirement, visual limit and protection method.
Illustrative No. 3 Surface
NO. 3
Illustrative visual reference only. Actual No. 3 appearance varies with the starting surface, abrasive sequence, polishing equipment, direction, pressure and supplier process. Use measured roughness and an approved sample where surface consistency is critical.
Finish Definition
What is a No. 3 stainless steel finish?
No. 3 is an intermediate polished stainless steel surface. It has visible parallel polishing lines and a coarser visual texture than No. 4.
The finish can be produced by controlled mechanical polishing and may be supplied on one or both sides depending on the product specification and supplier route. It is frequently treated as a useful intermediate stage when additional polishing will follow after fabrication.
The No. 3 designation does not define one universal Ra / Rz, abrasive grit, reflectivity or defect limit. When these characteristics matter, write them into the RFQ and verify them with actual measurement and an approved surface sample.
Define these points before approving a No. 3 finish
- Stainless steel grade and product form
- Starting surface / incoming mill finish
- Abrasive polishing route and grain direction
- Ra / Rz range where measurable roughness is required
- Reflectivity / color tolerance where applicable
- Approved sample and finish-limit reference
- Protective film, defect acceptance and cleaning guidance
Finish Evidence
Technical and application evidence for No. 3 finish approval
The page keeps the image count low: one technical evidence image and one application image in addition to the hero visual. Use verified production evidence before final technical approval.
Technical evidence image
Use one combined image showing the actual No. 3 polishing lines, Ra / Rz reading and approved sample or finish-limit comparison.
Application image
Use one real sheet, equipment panel or fabricated-part photo where the No. 3 polished stainless surface is visible.
Supply Specification
No. 3 finish stainless sheet, strip and fabricated-part ordering matrix
Define dimensions, visible side, grain direction, roughness requirement and protection method together. The table below is an RFQ checklist and does not represent live inventory.
Specify grade, thickness, width, length, polished side, grain direction and surface target.
Define slit width, edge condition, grain direction and protective handling.
Provide drawings, visible zones and whether No. 3 is final or an intermediate finish.
| Supply Form | Required Order Data | No. 3 Surface Control | Processing / Delivery Notes |
|---|---|---|---|
| No. 3 Sheet | Grade, thickness, width, length, quantity, tolerance and polished side | No. 3 designation, grain direction, Ra/Rz if required and approved sample | Confirm film, interleave, edge protection and packaging |
| No. 3 Strip | Grade, thickness, slit width, quantity and edge condition | Maintain the agreed polish direction and surface limit after slitting | Specify width tolerance and visible-side protection |
| Cut Blanks | Grade, thickness, blank dimensions, quantity and drawing if applicable | Define grain orientation relative to the blank / component | Confirm cutting sequence, film and surface handling |
| Fabricated Part | Drawing, grade, dimensions, quantity and visible finish zones | Define final or intermediate No. 3 finish and re-polishing criteria | Confirm whether final polishing occurs before or after fabrication |
Availability, dimensional limits, abrasive route and achievable surface consistency must be confirmed against the actual quotation.
Finish Selection
No. 3 vs No. 4 vs brushed vs 2B stainless steel finish
No. 3 is best understood as an intermediate polished finish. Select it when its coarser linear polish, processing role and measurable surface requirement match the project.
| Finish | Visual Character | Process Character | Selection Logic | Specification Note |
|---|---|---|---|---|
|
No. 3
This Page |
Coarse, visible linear polishing lines | Intermediate mechanical polish | When an intermediate or coarser polished finish is required | Specify grain + Ra/Rz / sample if critical |
| No. 4 | Finer general-purpose linear polish | Finer mechanical polishing route | When a more refined common polished finish is required | Do not substitute No. 3 and No. 4 without approval |
| Brushed | Directional decorative grain | Broad commercial abrasive-finish term | When a project-defined brushed appearance is specified | “Brushed” does not automatically mean ASTM No. 3 |
| 2B | Smooth, moderately reflective mill surface | Cold-rolled mill finish | When a standard mill finish is acceptable | No deliberate linear polished texture |
Processing Route
Typical processing route for No. 3 stainless steel
A repeatable No. 3 finish requires control of the starting surface, abrasive sequence, grain direction, final inspection and handling through fabrication.
Define Starting Surface
State the incoming mill finish and defects that must be removed before polishing.
Abrasive Preparation
Use the controlled abrasive sequence required to reach the approved No. 3 appearance.
Directional Polishing
Maintain the specified line direction and repeatable process conditions.
Ra / Rz Verification
Measure the surface where measurable roughness is part of project acceptance.
Visual Inspection
Check grain, tone, scratches and local variation against the approved sample.
Protect / Further Polish
Protect No. 3 when it is the final finish, or define the next polishing stage if it is intermediate.
Surface Control
Roughness, polishing route, reflectivity and cleaning guidance
The content matrix requires unique, reviewable finish data. Do not publish invented Ra/Rz or production capability values; use actual measurement and supplier evidence before final indexing.
Ra / Rz & Production Route
No. 3 does not create one universal roughness value. Actual roughness depends on the starting surface, abrasive route and process settings.
- Ra target: specify where required
- Rz target: specify where required
- Measurement direction / location: define in the inspection plan
- Abrasive route: record for repeatability
Reflectivity, Color & Defect Acceptance
The linear polish affects how the surface reflects light. Use controlled lighting and a finish-limit sample for appearance-critical applications.
- Define acceptable grain / tone variation
- Set cross-grain scratch criteria
- Set stop-mark and uneven-polish criteria
- Use reflectivity / color limits where applicable
Grades, Film & Cleaning
Confirm compatible grades and forms in the quotation. Protect the polished face during downstream handling and clean it without changing the approved linear surface.
- Grade / form: confirm by quotation
- Protective film / interleave: specify where needed
- Clean in the grain direction where practical
- Avoid uncontrolled abrasive rework after final inspection
Application Guidance
Where is No. 3 stainless steel finish used?
No. 3 is useful when a coarser polished stainless surface is acceptable or where additional polishing will follow during later fabrication.
Food-Processing Equipment
Project-specific panels and components where a coarser polished surface is accepted by specification.
Brewery Equipment
Stainless equipment components requiring a controlled linear polish before or after fabrication.
Commercial Kitchen Components
Parts where a functional polished surface is specified without requiring a finer No. 4 appearance.
Intermediate Polishing
Components supplied at No. 3 as a starting surface for later finer polishing after fabrication.
Architectural Components
Selected visible metalwork where a coarser linear texture is part of the approved finish.
Custom Polished Parts
Drawing-controlled parts requiring specified grain direction, roughness and final visual limits.
Standards & Equivalence
How No. 3 finish is specified for stainless steel sheet
The No. 3 designation should be combined with the correct material grade, product standard, dimensions, surface limits and visual acceptance criteria.
- ASTM A480 / A480M — No. 3 No. 3 is identified as an intermediate polished finish for stainless steel sheet, available on one or both sides.
- Polishing route Use the approved mechanical polishing route and grain direction required to reproduce the target appearance.
- Ra / Rz requirement Add measurable roughness limits, measurement method, location and direction when surface texture is critical.
- Visual approval Use an approved sample or finish-limit panel to control grain, reflectivity, scratches and local variation.
Do not assume No. 3, No. 4 and generic “brushed” finish are equivalent.
No. 3 is an intermediate polished finish and is generally coarser than No. 4. Generic brushed terminology may use different abrasive routes and visual acceptance standards.
The finish name does not define chemistry, mechanical properties, dimensions, exact Ra/Rz or complete defect criteria.
For critical work, specify the governing finish designation, roughness requirement, grain direction and approved sample.
Technical FAQ
No. 3 stainless steel finish FAQ
What is a No. 3 stainless steel finish?
Is No. 3 stainless steel the same as No. 4?
What is the typical No. 3 surface roughness?
Does No. 3 finish have a directional grain?
Can No. 3 be used before a finer polishing operation?
Can No. 3 stainless sheet be supplied with protective film?
How should No. 3 stainless steel be cleaned?
What information should be included in a No. 3 stainless steel RFQ?
Related Resources
Continue your stainless steel specification
Technical Evidence & Review
Data sources and document control for this No. 3 finish page
Required evidence sources
- Ra / Rz values should come from an actual measurement record or approved production test.
- Abrasive / polishing route should match the actual supplier process or production specification.
- Visual tolerance should use controlled-light close-ups and an approved / limit sample.
- Compatible grades, forms, protection and processing claims should match current quotation capability.
- Application images should be real project, production or permission-cleared evidence.
Document control
Technical Quote
Request a technical quote for No. 3 stainless steel
Send the grade, dimensions and polished-surface requirements together. For appearance-critical work, include the grain direction, Ra/Rz requirement and approved sample.
- Stainless steel grade
- Sheet, strip, blank or fabricated part
- Thickness × width × length
- Required quantity
- No. 3 finish designation
- Polished side + grain direction
- Ra / Rz or approved sample if required
- Protective film / processing requirement
- Destination, due date and inspection needs