October 17, 2026 | Tech Notes
Prepainted steel bound for exported appliances faces a newer gate: OEM audits now ask for RoHS / REACH test reports, and one failure cancels the qualification. Environmental performance is not a marketing phrase — it lives in two invisible places: the paint formulation and the pre-treatment passivation.
The substrate is the chassis of cost and performance. One coating line can run several:
| Substrate | Coating weight | Where it fits |
|---|---|---|
| Cold-rolled | None | Inner panels, dry indoor parts — lowest cost |
| Hot-dip galvanized | Z60–Z275 | The workhorse for appliance shells and doors — corrosion resistance scales with coating weight |
| Galvalume | AZ70–AZ150 | Back panels and humid climates — outlasts GI at equal coating weight |
| Aluminum / steel-clad Al | — | Premium decorative parts and liners — aluminum looks at steel cost |
Widths run 1000–1250 mm by order, finished gauges 0.15–0.8 mm, coil or sheet, colors matched to RAL codes or physical samples. Why chrome-free passivation became a gate is covered in a separate article.
The embossed series: after coating, the sheet passes engraved emboss rolls that press orange-peel, H-pattern or velvet grain into the surface. The texture adds depth, hides scratches and carries stiffness — the biggest volume goes to fridge side panels and chest freezer doors. Depth follows the part: 0.06–0.08 mm for side panels, 0.15 mm for liners, micrometer-checked every batch. How emboss depth is set is a separate article.
The printed series: a base coat is baked and set, the pattern — granite, wood grain, brushed — is transferred by a gravure cylinder onto the film, and a clear topcoat cures over it to lock the design in. Brushed and stone looks dominate appliance use, with pattern numbers selected from samples — increasingly popular on small-appliance shells and decorative panels.
Three statements settle the order: application and part (sets substrate and coating weight), target market (sets the compliance test package), surface and pattern (sets the line schedule). Send drawings or samples — quotes within 24 hours, custom colors strike off first and run only after your sign-off.
