Pre-painted steel (PPGI — pre-painted galvanised iron) is produced by painting galvanised sheet on a continuous line in the factory. The substrate is galvanised sheet; a primer and a paint layer are applied over it.
Factory paint gives a far more uniform thickness and better adhesion than painting done on site.
Technical specifications
| Substrate | Galvanised (Z100 – Z225) |
|---|---|
| Paint | Polyester 15 – 25 µm |
| Thickness | 0.35 – 1.20 mm |
| Colour | RAL chart |
| Standard | EN 10169 |
| Use | Roof, façade, sandwich panel |
What the paint thickness means
Polyester paint is applied in the 15–25 µm range. Thicker paint gives longer life and better colour retention.
In aggressive environments (coastal, industrial) a thicker paint and a higher substrate coating class are chosen together.
Two-layer protection
Protection on pre-painted sheet is in two layers: zinc beneath, paint above. The paint is a physical barrier, while the zinc gives cathodic protection at scratches and cut points.
That is why the substrate coating class (the Z value) matters on pre-painted sheet too; do not choose on colour alone.
Where it is used
- Sandwich panel and trapezoidal sheet production
- Façade cladding and curtain-wall panels
- Exterior surfaces of white goods
- Advertising and signage panels