| Base Metal | Hot-dip galvanized steel; aluminum-zinc coated steel; zinc-aluminum-magnesium coated steel | Metallic coating mass is commonly specified in g/m² and selected according to corrosion exposure and forming requirements | Determines corrosion resistance, edge protection, forming behavior, and compatibility with local standards | Use galvanized steel for widely standardized construction applications; consider alloy-coated substrates for demanding exposure or improved edge protection |
| Steel Grade and Yield Strength | Forming grade; structural grade; high-strength grade | Typical yield-strength ranges are approximately 140–280 MPa for forming grades and 280–550 MPa for many structural or high-strength grades | Affects load capacity, minimum bend radius, springback, roll-forming settings, and risk of cracking | Select the lowest strength that meets structural calculations when extensive forming is required |
| Steel Thickness | Light-gauge; medium-gauge; heavy-gauge | Common pre-painted coil thicknesses are approximately 0.30–1.20 mm, depending on the application and specification | Controls panel stiffness, span capability, dead load, handling, and material consumption | Verify thickness against structural design, profile geometry, fastener requirements, and local building codes |
| Coil Width | Slit coil; standard-width coil; custom-width coil | Typical construction supply widths range from approximately 600–1,250 mm, while wider or narrower widths may be available for specific lines | Influences yield, slitting waste, roll-forming efficiency, container utilization, and installation layout | Match coil width to the finished profile and allow for side-trim and dimensional tolerances |
| Primer System | Epoxy primer; polyester-compatible primer; corrosion-inhibiting primer | Primer thickness is often specified separately and may commonly be around 5–10 μm, subject to the coating system | Supports adhesion, corrosion protection, forming performance, and compatibility between substrate and topcoat | Choose the primer according to exposure category, forming severity, and the selected topcoat chemistry |
| Topcoat Chemistry | Standard polyester; silicone-modified polyester; polyurethane; polyvinylidene fluoride-based coating | Total organic coating thickness commonly falls within approximately 15–35 μm, depending on the system and service requirement | Affects color retention, chalking resistance, flexibility, scratch resistance, chemical resistance, and expected maintenance interval | Use standard polyester for general building applications; select higher-performance systems for severe ultraviolet, coastal, or chemical exposure |
| Coating Gloss | Low gloss; medium gloss; high gloss; matte finish | Gloss is normally measured at a defined angle, commonly 60°, using a recognized test method | Influences appearance, glare, perceived surface texture, and the visibility of minor surface imperfections | Specify the measurement angle and tolerance instead of relying only on terms such as “shiny” or “matte” |
| Color Control | Standard color reference; project-specific color; multi-coil color matching | Define color using an approved physical sample or an objective color measurement system such as CIELAB with agreed tolerances | Reduces visible variation between production lots, building elevations, replacement panels, and international shipments | Approve a master sample before production and specify inspection conditions, viewing angle, and allowable variation |
| Exposure Environment | Rural; urban; industrial; coastal; high-UV; high-humidity | Classify the environment using a recognized corrosion classification approach, such as ISO 12944, where applicable | Determines the required metallic coating, paint system, edge protection, detailing, and inspection frequency | Use a higher-performance system for salt spray, persistent condensation, industrial pollutants, or strong solar exposure |
| Forming Requirement | Simple bending; roll forming; deep forming; tight-radius forming | Specify minimum internal bend radius relative to sheet thickness; the exact limit depends on grade, coating system, and forming direction | Affects cracking, delamination, exposed metal at bends, dimensional accuracy, and production speed | Request forming test data for tight profiles and confirm whether the visible side must be formed over the inside or outside radius |
| Application | Roofing; wall cladding; sandwich panels; ceiling systems; doors; architectural flashings | Requirements vary for exposed surfaces, concealed surfaces, cut edges, fire performance, acoustic design, and structural loading | Defines the required thickness, strength, coating durability, profile geometry, and installation method | Select the coil only after confirming the complete panel or component design, not from color alone |
| Applicable Standard | ASTM-based; EN-based; ISO-based; regional construction specification | Common references include EN 10169 for continuously organic-coated steel, EN 10346 for continuously hot-dip coated steel, and ASTM A755/A755M for prepainted steel sheet | Ensures that coating mass, mechanical properties, dimensional tolerances, testing, and documentation are comparable across markets | State the governing standard, edition, testing method, and acceptance criteria in the purchase specification |
| Surface Protection During Transport | Removable protective film; moisture-resistant wrapping; edge protection; export packaging | Packaging should prevent water ingress, abrasion, coil movement, and condensation-related storage staining | Reduces transit damage, white rust, surface scratches, and claims caused by long-distance or multimodal shipment | Define packaging, lifting points, storage orientation, maximum storage period, and film-removal requirements |
| Quality Documentation | Mill test certificate; coating test report; dimensional inspection; color and gloss record | Documentation should identify grade, thickness, width, coating mass, paint system, batch or coil number, test results, and applicable standard | Supports customs clearance, traceability, project approval, incoming inspection, and warranty evaluation | Require document review before shipment and retain samples or records for multi-phase global projects |
