Painted steel and pre-coated coil are widely used in industries like construction, automotive, appliances, and manufacturing due to their durability, corrosion resistance, and aesthetic appeal. However, customers have specific requirements when ordering these materials to ensure they meet performance and application needs.
In this blog, we’ll break down the most common customer specifications for painted steel and pre-coated coil, helping buyers and suppliers navigate the key factors that impact quality, performance, and cost.
What is Painted Steel or Pre-Coated Coil?
Painted steel (also known as pre-painted or pre-coated coil) is steel that has been coated with a layer of paint or other protective coatings before being formed into finished products. This process enhances corrosion resistance, weather durability, and appearance.
Common Uses of Pre-Coated Steel:
🏠 Construction: Roofing, siding, metal panels
🚗 Automotive: Exterior panels, trim parts
📦 Appliances: Refrigerators, ovens, washing machines
📢 Signage & Displays: Commercial signage, billboards
Common Customer Specifications for Painted Steel
When ordering painted steel or pre-coated coil, customers specify key properties to ensure the material meets their needs. Here are the most common specs:
1. Substrate Type (Base Metal)
The base metal affects the strength, corrosion resistance, and application of the coated steel. Common substrates include:
✔ Galvanized Steel (GI): Zinc-coated for corrosion resistance
✔ Galvalume (AZ): Aluminum-zinc alloy for extra durability
✔ Cold-Rolled Steel (CR): Smooth, high-precision surface for detailed applications
✔ Aluminum: Lightweight, corrosion-resistant alternative
💡 Example: A roofing manufacturer may request Galvalume-coated steel for better weather resistance.
2. Coating Type (Paint System)
The type of coating determines durability, color retention, and weather resistance. Common options include:
✔ Polyester (PE): Cost-effective, good for indoor and mild outdoor use
✔ Silicone-Modified Polyester (SMP): Improved weather and UV resistance
✔ Polyvinylidene Fluoride (PVDF or Kynar 500®): High-performance, fade-resistant, ideal for harsh environments
✔ Epoxy: Excellent adhesion and chemical resistance, often used as a primer
💡 Example: A building contractor may specify PVDF-coated steel for a commercial roof to ensure long-term UV resistance.
3. Color & Gloss Level
Customers often specify exact colors and gloss levels for branding, aesthetics, or functional reasons.
✔ Standard Colors: Pre-formulated industrial colors (e.g., RAL, Pantone)
✔ Custom Colors: Color-matching for brand identity or specific design needs
✔ Gloss Levels:
Matte (Low Gloss, <10 GU) – Minimal shine, great for modern aesthetics Satin (Medium Gloss, 10–35 GU) – Balanced appearance with some reflectivity Glossy (High Gloss, 35+ GU) – Shiny, vibrant finish 💡 Example: An appliance manufacturer may require high-gloss white steel for refrigerators to match industry standards. 4. Coating Thickness (Paint Film Thickness, PFT) The thickness of the coating impacts durability and protection. It is measured in microns (µm) or mils. ✔ Typical Paint Thickness Ranges: Primer: 5–10 µm Topcoat: 15–25 µm Total Coating Thickness: 20–35 µm (varies by application) 💡 Example: A steel panel manufacturer may specify a total thickness of 30 µm for exterior durability. 5. Corrosion Resistance (Salt Spray & Weathering Tests) Corrosion resistance is critical for outdoor and industrial applications. Customers may request testing per: ✔ Salt Spray Test (ASTM B117): Simulates corrosion resistance in a humid, salty environment ✔ UV Resistance (QUV Test – ASTM G154): Measures color retention and fading over time ✔ Humidity Test: Ensures resistance to moisture damage 💡 Example: A coastal construction project may require a minimum of 1,000 hours of salt spray resistance for roofing materials. 6. Surface Finish & Texture The texture of pre-coated steel affects its appearance and performance. Common finishes include: ✔ Smooth: Sleek, polished appearance ✔ Embossed: Textured for grip or decorative appeal (e.g., stucco pattern for roofing) ✔ Wrinkled/Matte: Diffuses light, reduces glare ✔ Brushed or Patterned: Aesthetic appeal for high-end applications 💡 Example: A furniture manufacturer may request embossed pre-coated steel for decorative panels. 7. Formability & Bend Test Requirements Painted steel needs to withstand bending, stamping, and forming without cracking. Common tests include: ✔ T-Bend Test: Measures flexibility of the coating (e.g., "0T" means no cracking when bent) ✔ Pencil Hardness Test: Assesses scratch resistance (e.g., H, 2H) ✔ Impact Resistance: Ensures coating remains intact under mechanical stress 💡 Example: A metal roofing supplier may specify a minimum 2T bend requirement to ensure the coating doesn’t crack during panel forming. 8. Backside Coating Requirements The backside (reverse side) coating protects against corrosion and enhances adhesion. Customers may specify: ✔ Primer + Back Coat: Basic protection for hidden surfaces ✔ Double-Sided Paint Coating: If both sides are visible or exposed to elements ✔ Adhesion Coatings: For improved bonding in lamination or composite panels 💡 Example: A manufacturer using pre-coated steel for sandwich panels may require a primer-coated backside for adhesive bonding. Final Thoughts Ordering painted steel or pre-coated coil requires detailed specifications to ensure the material meets performance and aesthetic needs. ✅ Choose the right base metal (galvanized, Galvalume, aluminum, etc.) ✅ Select the appropriate coating system (polyester, PVDF, SMP, etc.) ✅ Specify color, gloss, and texture for branding and appearance ✅ Ensure proper coating thickness for durability ✅ Request corrosion and durability testing based on environmental exposure ✅ Define forming and bending requirements to avoid cracking By understanding and specifying these factors, customers can ensure they get high-quality, long-lasting pre-coated steel for their applications. 🚀 Need help selecting the right painted steel specs for your project? Let’s discuss in the comments!
