If you’re after stainless steel that blends durability with a sleek, modern look—think kitchen appliances, architectural panels, or elevator cladding—304 4 brushed stainless steel is the answer. The “#4” refers to its signature fine, linear finish, while “304” guarantees reliable corrosion resistance. This guide breaks down everything you need to know to choose, use, and maintain this popular material.
1. 304 4 Brushed Stainless Steel: Material Overview & Properties
304 4 brushed stainless steel combines the strength of 304 grade with the aesthetic appeal of a brushed finish. Here’s what makes it stand out:
Core Material Properties
| Property | Typical Value | Why It Matters for Your Projects |
|---|---|---|
| Chemical Composition | 18–20% Chromium, 8–10.5% Nickel, ≤0.08% Carbon | Chromium forms a passivation layer (rust-resistant film); nickel keeps it austenitic (non-magnetic) |
| Yield Strength | 205 MPa (29,700 psi) | Resists bending in high-use items (e.g., countertop edges) |
| Tensile Strength | 515 MPa (74,700 psi) | Strong enough for structural parts (e.g., wall panels) |
| Corrosion Resistance | Excellent (resists water, mild acids) | Won’t rust in kitchens, bathrooms, or indoor spaces—though less durable than 316 in saltwater |
| Magnetic Properties | Non-magnetic (annealed) | Safe for electronics and medical equipment |
| #4 Brushed Finish | Linear texture, Ra 0.8–1.6 µm | Hides fingerprints and minor scratches (unlike mirror polish) |
304 vs. 316 Comparison: 304 4 brushed steel is ideal for indoor use, while 316 (with molybdenum) is better for coastal/outdoor spaces. A café used 304 4 brushed steel for indoor countertops—they stayed scratch-free for 5 years—while outdoor tables (exposed to rain) needed 316 to avoid rust.
2. 304 4 Brushed Stainless Steel: Manufacturing & Finishing Processes
The #4 brushed finish is created through a precise mechanical process that gives 304 steel its distinct look. Here’s how it’s done:
Step 1: Base Steel Preparation
First, 304 stainless steel is cold-rolled into sheets (starting with a 2B mill finish—smooth but matte). This base sheet is cleaned to remove oil, dirt, and mill scale (a rough oxide layer) using sandblasting or chemical cleaning.
Step 2: Creating the #4 Brushed Finish
- Grit Sequence Selection: The sheet passes through a stainless steel brushing machine fitted with abrasive belts. The process uses a specific grit sequence—typically 120-grit (to shape the texture) followed by 180–240-grit (to refine it into a fine, uniform line).
- Brushing Direction: The abrasive belts move in one direction (usually horizontal) to create parallel linear lines—this is what defines the #4 finish.
- Ra Value Check: After brushing, the surface is tested for Ra value (roughness average). A #4 finish requires an Ra of 0.8–1.6 µm—smooth enough to touch, textured enough to hide fingerprints.
Step 3: Post-Finish Protection
- Passivation: The brushed sheet undergoes a nitric acid bath to strengthen the passivation layer—critical for maintaining corrosion resistance (brushing can expose tiny areas of unprotected steel).
- Quality Control: Inspectors check for consistent texture (no uneven lines) and confirm the Ra value meets standards (e.g., ISO finish #4).
Example: A manufacturer once skipped the 240-grit step—their #4 finish had rough, visible scratches. Adding the final grit step fixed the issue and made the finish sellable.
3. 304 4 Brushed Stainless Steel: Applications & Industry Use-Cases
304 4 brushed steel’s blend of aesthetics and durability makes it a staple in multiple industries:
1. Kitchen & Food Industry
- Appliances: Refrigerator doors, oven fronts, and dishwasher panels use 304 4 brushed steel—its texture hides fingerprints from daily use. A major appliance brand reported 30% higher sales for fridges with #4 brushed finishes (vs. mirror polish).
- Food-Grade Countertops: Restaurants and commercial kitchens use 304 4 brushed steel countertops—they’re easy to clean, resist food stains (e.g., tomato sauce), and meet NSF/ANSI 51 food-safety standards.
2. Architecture & Construction
- Architectural Wall Panels: Hotels and offices use 304 4 brushed steel for accent walls—its linear texture adds depth to spaces. A hotel lobby in Chicago used 500 sq. meters of #4 brushed panels—they still look new after 8 years.
- Elevator Cabin Cladding: Elevator interiors rely on 304 4 brushed steel—its durability resists dents from luggage, and the finish hides scuffs from foot traffic.
3. Medical & Automotive
- Medical Equipment: Exam tables and instrument carts use 304 4 brushed steel—its non-porous surface is easy to sterilize (meets FDA standards).
- Automotive Trim: Luxury cars use #4 brushed steel for dashboard accents—its texture adds a premium look without showing dust.
4. 304 4 Brushed Stainless Steel: Fabrication & Forming Techniques
Fabricating 304 4 brushed steel requires care to avoid damaging the finish. Here are best practices:
Key Fabrication Methods
| Technique | Tips for Protecting the #4 Finish | Use Case Example |
|---|---|---|
| Laser Cutting | Use nitrogen assist gas (prevents oxidation) and cover the finish with a protective film during cutting. | Cutting decorative shapes for wall panels |
| Bending | Use a press brake with rubber-coated dies to avoid scratching. Keep the bending radius ≥1x the sheet thickness (e.g., 2mm sheet needs a 2mm radius). | Making countertop edges or panel frames |
| Welding | Use TIG welding with ER308L filler wire. After welding, remove discoloration using a stainless steel brush (matching the #4 finish direction) and re-passivate. | Joining countertop sections |
| Adhesive Bonding | Use a high-strength epoxy (e.g., 3M VHB tape) instead of drilling (drilling can chip the finish). Clean the surface with isopropyl alcohol first for better adhesion. | Attaching wall panels to studs |
Warning: A fabricator once used a steel brush to clean welds—this left crosswise scratches that ruined the #4 finish. Using a brush that follows the finish’s linear direction fixed the problem.
5. 304 4 Brushed Stainless Steel: Surface Care, Cleaning & Maintenance
With proper care, 304 4 brushed stainless steel can last decades. Here’s how to keep it looking new:
Routine Cleaning Steps
- Daily Cleaning: Wipe with a soft, lint-free cloth (microfiber works best) and warm, soapy water. Avoid abrasive sponges (they scratch the finish).
- Tough Stains: For grease or food stains, use a stainless steel brush finish cleaner (e.g., Bar Keepers Friend) applied in the direction of the brushed lines. Rinse thoroughly and dry immediately.
- Fingerprint Removal: Use a 50/50 mix of water and vinegar—spray on, wipe with a cloth, and dry. For frequent use areas (e.g., fridge doors), apply a fingerprint-resistant coating (available at hardware stores) every 6 months.
Scratch Repair
- Minor Scratches: Use a 320-grit sanding pad, sand gently in the direction of the brushed lines, then wipe with a clean cloth.
- Deep Scratches: Hire a professional to re-brush the area (they have the right grit belts to match the #4 finish).
Maintenance Schedule
| Frequency | Task |
|---|---|
| Daily | Wipe with soapy water and dry |
| Weekly | Clean with vinegar to remove fingerprints |
| Every 6 Months | Apply fingerprint-resistant coating |
| Annually | Check for rust spots; re-passivate if needed |
6. 304 4 Brushed Stainless Steel: Standards, Certifications & Compliance
To ensure you’re getting high-quality 304 4 brushed steel, look for these standards and certifications:
Key Standards
| Standard Organization | Relevant Specs | Focus Area |
|---|---|---|
| ASTM (U.S.) | ASTM A240 | Defines 304 steel quality and #4 finish requirements |
| ISO (Global) | ISO finish #4 | Sets Ra value (0.8–1.6 µm) for brushed finishes |
| EN (Europe) | EN 10088-2 grade 1.4301 | Equivalent to 304; ensures finish consistency |
Critical Certifications
- NSF/ANSI 51: Proves suitability for food-contact surfaces (e.g., countertops, appliances).
- FDA Compliance: Mandatory for medical equipment and food-processing parts.
- RoHS Compliance: Ensures no harmful substances (e.g., lead) for consumer goods.
- Mill Test Certificate (EN 10204 3.1): Confirms chemical composition, mechanical properties, and finish quality—always ask suppliers for this.
7. 304 4 Brushed Stainless Steel: Supply Chain, Pricing & Procurement
Buying 304 4 brushed steel efficiently means understanding costs, lead times, and supplier requirements. Here’s what you need to know:
Pricing (2024 Estimates)
| Product Type | Price per kg | Price Difference vs. 2B Finish |
|---|---|---|
| 304 #4 Brushed Sheets (1mm thick) | $4.00–$4.80 | 15–20% higher (brushing adds labor/cost) |
| 304 #4 Brushed Coils (1mm thick) | $3.80–$4.50 | 10–15% higher than 2B coils |
Cost Driver: Nickel prices (304 has 8–10.5% nickel) affect costs—if LME nickel rises 10%, 304 #4 brushed steel prices typically rise 8–9%.
Procurement Tips
- MOQ (Minimum Order Quantity): Most suppliers require 100kg for sheets, 500kg for coils. Smaller orders (e.g., 50kg) are possible but cost 25% more.
- Lead Time: 2–3 weeks for stock sizes (e.g., 1x2m sheets); 4–6 weeks for custom sizes/coils.
- Supplier Selection: Choose suppliers who specialize in brushed finishes (general steel suppliers may have inconsistent texture). Ask for a sample before ordering to check the finish.
- Packaging: Request sheets/coils wrapped in VCI film (prevents rust) and separated by foam (avoids finish damage during shipping).
Example: A restaurant owner ordered 200kg of 304 #4 brushed steel sheets (stock 1x2m size). They received the order in 2 weeks and saved $300 vs. custom sizes.
Yigu Technology’s Perspective
At Yigu Technology, 304 4 brushed stainless steel is our top choice for clients needing both aesthetics and durability. We supply ASTM A240/EN 1.4301 304 #4 brushed sheets (0.5–3mm thick, 1x2m/2x3m stock sizes) and coils, with Ra values strictly between 0.8–1.6 µm. We offer custom cutting/ bending and provide samples for finish approval. All our products come with EN 10204 3.1 certificates and NSF/ANSI 51 compliance for food-grade use. We also track nickel prices daily, helping clients lock in rates. For one hotel project, we supplied 1,000 sq. meters of #4 brushed panels—our consistent texture made installation seamless and the client’s space look cohesive.
FAQ
- Can 304 4 brushed stainless steel be used outdoors?
It’s not recommended for long-term outdoor use (e.g., patio furniture). Rain, salt, and humidity will cause rust within 2–3 years. If you must use it outdoors, apply a marine-grade clear coat every 6 months and cover it during bad weather. - How do I tell if my stainless steel is 304 #4 brushed or a cheaper grade?
Use a magnet—304 is non-magnetic (annealed), while cheaper grades (e.g., 430) are magnetic. Also, check the finish: 304 #4 brushed steel has uniform, fine lines (Ra 0.8–1.6 µm), while cheaper grades may have uneven or rough texture. - Will welding 304 #4 brushed stainless steel ruin the finish?
Welding can cause discoloration (bluing) near the weld, but it won’t ruin the finish. Fix it by gently sanding the discolored area with a 240-grit pad (in the direction of the brushed lines) and then re-passivating with a stainless steel cleaner. This restores the finish and corrosion resistance.
