Stainless Steel Surface Finish Chart and Ra Guide

Finish Chart · Ra Guide · RFQ Support

Stainless Steel Surface Finish Chart: 2B, BA, No.4, HL, 8K & Ra Guide

Compare No.1, 2D, 2B, BA, No.4, hairline and mirror finishes, then translate a visual requirement into a measurable roughness target, inspection plan and purchase specification.

A finish name is not a complete acceptance criterion. Mill route, abrasive grit, grain direction, gloss, protection film, sampling method and actual Ra results can change the delivered appearance.

Use the finish lookup Request finish verification

7core finish families

µm + µintwo roughness units

RFQ readycopyable lookup summary

Quick answer: finish designation and Ra solve different problems

A finish designation describes the production route and expected appearance. Ra measures average surface roughness. Two surfaces can overlap in Ra but still look different because reflectivity, grain pattern and polishing direction are not captured by Ra alone.

For routine sourcing, specify the finish name, grade, dimensions, grain direction and protective film. For hygienic, architectural or tightly controlled projects, add a numeric Ra limit, approved sample, gloss or visual standard, sampling plan and inspection report.

Finish name answers “what should it look like?”

Examples include 2B, BA, No.4, HL and 8K. Commercial practice can vary by mill and finishing line.

Ra answers “how rough is the measured profile?”

It does not fully describe gloss, waviness, color, scratch pattern, grain direction or reflectivity.

Approved samples reduce visual disputes

For visible panels, agree the sample, viewing direction, lighting, film and lot-consistency criteria before production.

Popular grade and finish paths

Surface finish cannot compensate for the wrong alloy. Start with the service environment, then choose the visual or functional finish.

View all stainless grades →

201 Stainless Steel

Cost-focused

Common for indoor decorative sheet, kitchenware and light fabrication. Confirm corrosion exposure before substituting it for 304.

Review 201 finish considerations →

304 Stainless Steel

General purpose

Widely supplied in 2B, BA, No.4 and HL for equipment, tanks, panels, kitchen products and architecture.

Review 304 grade guide →

316L Stainless Steel

Hygienic / welded

Useful for chemical, food, pharmaceutical and welded systems where grade, weld condition and cleanability must be controlled together.

Review 316L surface requirements →

420 Stainless Steel

Polished parts

Martensitic grade for blades, instruments and wear parts. Final polish depends on heat treatment, grinding control and surface integrity.

Review 420 polishing guidance →

430 Stainless Steel

Appliance / decorative

Ferritic, magnetic and cost-effective for appliance panels and indoor decoration, often supplied as BA, No.4 or hairline.

Review 430 finish selection →

2205 Duplex

Chloride service

Higher-strength duplex grade for demanding corrosion service. Finish, weld condition and deposits still affect localized corrosion behavior.

Review 2205 grade guide →

Stainless steel finish and Ra lookup

Use forward lookup when the drawing names a finish. Use reverse lookup when the drawing gives only a target Ra value.

Surface finish

Target Ra

Unit

Conversion used: 1 µin = 0.0254 µm. Ranges are procurement references, not guaranteed acceptance limits.

Summary for RFQs, email or internal approval

Lookup result

Smooth cold-rolled mill finish.

0.2–0.5 µm 8–20 µin

Confirm real material, finish route, direction and measured roughness when the project has a strict acceptance criterion.

Typical use: tanks, housings and general fabrication.
Appearance: smooth, semi-bright and non-directional.
Buyer note: common base finish for further polishing.

Stainless steel surface finish chart with typical Ra ranges

Use these ranges for initial discussion. Contract acceptance should follow the agreed specification, sample and actual inspection results.

Common stainless sheet and plate finish references. Commercial naming and roughness can vary by producer and finishing route.
Finish	Typical Ra	Appearance / process	Typical applications	Critical buying note
No.1	2.5–6.3 µm 100–250 µin	Hot rolled, annealed and pickled; coarse, matte and non-decorative.	Heavy plate, tanks, structures, furnace and industrial fabrication.	Confirm pickling quality, scale removal, plate flatness and downstream weld or machining needs.
2D	0.8–2.0 µm 30–80 µin	Cold rolled, annealed and pickled; smooth matte surface without final skin pass.	Industrial parts, roofing, exhaust components and forming applications.	Often chosen for function rather than appearance; verify availability by grade and thickness.
2B	0.2–0.5 µm 8–20 µin	Cold rolled, annealed, pickled and lightly skin passed; smooth semi-bright mill finish.	Tanks, enclosures, food equipment, covers and general fabrication.	Ra can overlap BA, but visual reflectivity differs. Specify film when appearance matters.
BA	0.05–0.20 µm 2–8 µin	Bright annealed in a controlled atmosphere; smooth and reflective.	Appliances, kitchenware, decorative trim and clean visible parts.	Confirm brightness, haze, gloss, coil width and whether the finish is mill BA or subsequently polished.
No.4	0.4–0.8 µm 15–30 µin	Short directional brushed or satin grain produced with abrasive finishing.	Elevator panels, kitchen equipment, wall panels and architectural trim.	State abrasive grit or approved sample, grain direction, gloss, film type and panel orientation.
HL	0.5–1.0 µm 20–40 µin	Long, continuous directional hairline grain with a decorative appearance.	Doors, frames, cladding, furniture, elevator interiors and premium panels.	Direction and lot consistency are critical. Mark arrows on film or packing when installation orientation matters.
8K / No.8	0.01–0.05 µm 0.4–2 µin	Multi-stage mirror polishing with high reflectivity and minimal visible grain.	Luxury interiors, signage, reflectors, feature walls and decorative ceilings.	Define mirror level, image clarity, waviness, pinholes, scratches, film and handling requirements.

Important: typical Ra values do not guarantee compliance with a specific ASTM, EN, JIS or customer specification. Finish designation, roughness, gloss, visual quality, grain direction and inspection method should be written separately when they are acceptance criteria.

2B vs BA vs No.4 vs HL vs 8K

This comparison focuses on commercial selection rather than treating finish names as rigid roughness grades.

Finish	Directionality	Reflectivity	Scratch visibility	Typical cost	Best fit
2B	Non-directional	Low to medium	Moderate	Low	General industrial sheet, tanks and equipment panels.
BA	Non-directional	Medium to high	More visible than satin grain	Medium	Appliances, kitchenware and bright clean surfaces.
No.4	Directional	Low to medium	Good at masking light handling marks	Medium to high	Kitchen equipment, elevators and public-facing panels.
HL	Strongly directional	Medium	Grain helps mask minor marks	Medium to high	Architectural panels, doors, trim and premium interiors.
8K	Minimal visible grain	Very high	Highly visible	High	Luxury decoration, signage and high-reflection applications.

Application-based finish selection

Use the application to decide which parameters need to be controlled beyond the finish name.

Food & pharmaceutical

Control cleanability, welds and actual roughness

2B or BA may be acceptable base surfaces, while hygienic equipment can require controlled mechanical polishing or electropolishing. Specify internal and external Ra separately for tube or vessel systems.

Review 316L stainless steel and the pipe and tube supply page.

Architecture

Control grain direction, color and replacement matching

No.4 and HL are common for visible panels. For large elevations, approve samples and confirm orientation, gloss, lot matching, film arrows, fabrication sequence and replacement-panel strategy.

See the sheet and plate product page and surface finishing service.

Industrial fabrication

Avoid paying for appearance that the project does not need

No.1, 2D or 2B can be more economical for hidden tanks, frames and machinery. Focus on grade, flatness, tolerance, weld preparation, contamination control and final cleaning.

Use the tolerance calculator before finalizing the RFQ.

Project-specific finishes beyond the basic chart

These treatments need project-specific samples and acceptance criteria; they should not be reduced to one universal Ra value.

Electropolished

Used for selected hygienic, semiconductor and corrosion-sensitive systems. Specify base condition, material removal, passivation, Ra and cleanliness requirements.

Bead blasted

Creates a uniform matte appearance, but media, pressure and contamination control affect color, texture and corrosion performance.

PVD

PVD color coating

Decorative color requires approved color standard, substrate finish, coating system, lot consistency and protective film.

AFP

Anti-fingerprint

Clear coatings can reduce fingerprints and cleaning effort. Confirm chemistry compatibility, bending behavior, UV exposure and repair method.

Finish quality control and RFQ checklist

A good inquiry separates material identity, dimensional requirements, finish appearance and measurable inspection criteria.

Quality control

Inspection points before shipment

Verify grade, heat number and MTC traceability.
Check base finish before brushing, polishing or coating.
Measure Ra using the agreed cutoff, direction and sampling plan.
Inspect gloss, haze, grain continuity, scratches, pits and waviness.
Confirm panel-to-panel color and direction under consistent lighting.
Check film adhesion, film arrows, edge exposure and residue risk.
Protect finished surfaces during cutting, forming, packing and loading.

RFQ essentials

Information to send the supplier

Grade and standard: for example 304 / S30400 / 1.4301.
Product form, thickness, width, length and tolerance.
Base finish and final finish: 2B → No.4, BA → HL, etc.
Target Ra, gloss or approved sample reference.
Abrasive grit, grain direction and orientation marks.
PE/PVC film type, thickness, color, adhesive and laser compatibility.
Inspection records, photos, sample approval and third-party inspection.
Packing method, paper interleave, pallets, crates and destination port.

Practical RFQ example: “304 stainless sheet, ASTM A240, 1.2 × 1219 × 2438 mm, No.4 directional finish on one side, approved sample reference SF-04, target Ra 0.4–0.8 µm, grain along 2438 mm, laser-compatible PE film, visual inspection under agreed lighting, seaworthy pallet packing.”

Market and procurement updates

Finish premiums, origin, duties, alloy costs and quote validity can change the landed cost even when the technical finish stays the same.

Market update 3 Aug 2026

China Stainless Prices Rise CNY 50–100

Review the reported 201 and 304 price movement, alloy-cost support, inventory pressure and buyer implications for August quotations.

Read the August market update →

Trade update 13 Jul 2026

Japan Provisional AD Duties

Cold-rolled stainless buyers should verify producer, origin, grade, finish, HS classification and landed-cost exposure.

Review the provisional duty update →

Trade investigation 23 Jun 2026

Japan Preliminary AD Ruling

See why grade chemistry, surface finish, thickness, width, producer identity and shipping documents matter in Japan-bound orders.

Read the preliminary ruling guide →

Products, processing services and calculators

Move from a finish decision to material supply, processing, inspection and quotation.

Stainless Steel Sheet / Plate

Source No.1, 2B, BA, No.4, HL and polished flat products with size, film and packing requirements.

View sheet and plate →

Stainless Steel Coil

Specify base finish, coil width, weight, edge, film and downstream slitting or cut-to-length processing.

View stainless steel coil →

Pipe / Tube

Define external and internal finish separately for decorative, hygienic and process piping applications.

View pipe and tube →

Surface Finishing Service

Combine base material with No.4, hairline, 6K, 8K, super mirror and protective film.

View surface finishing →

Cut-to-Length & Slitting

Protect directional surfaces while converting coil into sheets or narrow strip with controlled dimensions.

Cut-to-length service →
Slitting service →

Export Packing

Use film, interleaving, edge protection, pallets, crates and careful loading for finish-sensitive material.

View export packing →

Grade Equivalents

Cross-reference ASTM, UNS, EN, JIS, GOST and GB designations.

Open grade chart →

Metal Gauge Chart

Convert gauge into nominal stainless sheet thickness in mm and inch.

Open gauge chart →

PREN Calculator

Compare alloy-based pitting resistance before selecting a surface for chloride service.

Open PREN calculator →

Metal Weight Calculator

Estimate theoretical sheet, plate, tube and bar weight for quotations and freight planning.

Calculate metal weight →

Need a finish recommendation and quotation?

Send the grade, product form, size, base finish, target finish, Ra limit, grain direction, film, quantity and destination. Include an approved sample or drawing when appearance is critical.

Send finish-based RFQ WhatsApp sales

Email sales@xrtgsteel.com

WhatsApp +86 182 6153 5591

Contact page xrtgsteel.com/contact-xrtgsteel/

Stainless steel surface finish FAQ

Answers focus on practical procurement, inspection and application questions.

What is a stainless steel surface finish chart?

It is a procurement reference that compares common finish names, typical roughness ranges, appearance, processing route and applications. It helps buyers translate 2B, BA, No.4, HL, 8K and other terms into a clearer RFQ.

Are the Ra values guaranteed for every stainless sheet or coil?

No. They are indicative ranges. Actual results depend on the steelmaker, grade, thickness, annealing and pickling route, skin pass, abrasive grit, line speed, polishing direction, measuring instrument and sampling method.

What is the difference between 2B and BA stainless steel?

2B is a smooth, semi-bright cold-rolled mill finish normally completed with a light skin pass. BA is bright annealed in a controlled atmosphere and is generally more reflective. Their Ra values can overlap, so appearance cannot be defined by Ra alone.

What is the difference between No.4 and hairline finish?

Both are directional abrasive finishes. No.4 normally has a shorter satin grain, while hairline has longer continuous lines. Supplier practice varies, so approve a sample and specify direction, grit or visual reference.

Is 8K the same as No.8 mirror finish?

They are often used as commercial mirror-finish terms, but image clarity, gloss, waviness and defect limits can differ between suppliers. A mirror label alone is not enough for a high-visibility project.

Which stainless finish is best for food or pharmaceutical equipment?

The answer depends on the process, cleaning method, weld condition and hygiene standard. 2B or BA may be acceptable for some surfaces, while product-contact areas can require controlled mechanical polishing or electropolishing with a specified maximum Ra.

Does a smoother surface always provide better corrosion resistance?

A smoother, clean and properly passivated surface can reduce sites where deposits accumulate, but alloy grade, temperature, chlorides, crevices, weld heat tint and contamination remain critical. Surface finish cannot turn an unsuitable grade into a suitable one.

What should I include in a finish-based stainless steel inquiry?

Send the grade, standard, product form, dimensions, base finish, final finish, Ra or gloss requirement, grain direction, approved sample, film, quantity, inspection scope, packing and destination port.

201

1.4372

X12CrMnNiN17-7-5

304

1.4301

X5CrNi18-10

304L

1.4307

X2CrNi18-9

309S

1.4833

X12CrNi23-13

310S

1.4845

X8CrNi25-21

316

1.4401

X5CrNiMo17-12-2

316L

1.4404

X2CrNiMo17-12-2

316Ti

1.4571

X6CrNiMoTi17-12-2

321

1.4541

X6CrNiTi18-10

410

1.4006

X12Cr13

420

1.4021

X20Cr13

430

1.4016

X6Cr17

2205

1.4462

X2CrNiMoN22-5-3

2507

1.4410

X2CrNiMoN25-7-4

904L

1.4539

X1NiCrMoCu25-20-5