01How the process works
After pretreatment (degreasing and conversion coating, or blasting), powder is sprayed with electrostatic guns, sticks to the earthed part and is cured at around 180 to 200 °C. Two coat systems use a primer and a topcoat.
Pretreatment quality decides adhesion and corrosion resistance; cure decides mechanical and chemical resistance. Film thickness, adhesion, gloss, colour and cure tests are routine, with salt spray for corrosion classes.
- Pretreatment. Cleaning and conversion coating or blasting.
- Drying. Water removed.
- Application. Electrostatic powder spray.
- Curing. Oven cure at specified time and temperature.
- Testing. DFT, adhesion, gloss, colour.
02What typically goes wrong
| Defect | Typical cause | How it is found |
|---|---|---|
| Poor adhesion | Pretreatment, contamination | Cross cut test |
| Undercure | Oven profile | Solvent rub test, impact |
| Low or excess thickness | Gun settings, Faraday cage areas | DFT gauge |
| Orange peel and craters | Powder, contamination | Visual |
| Colour mismatch | Batch, cure | Spectrophotometer |
| Edge corrosion | Thin edge coverage | Salt spray |
03Where an inspector should look
01
Before production
- Coating system and colour
- Pretreatment chemistry
- Oven profile
02
During production
- Pretreatment bath checks
- Oven temperature logging
03
After production
- DFT readings
- Cross cut adhesion
- Visual, gloss and colour
04Standards and references
ISO 2409 (cross cut), ISO 2813 (gloss), Qualicoat and GSB specifications, ISO 9227 (salt spray).
Standards are named for orientation. The applicable edition and acceptance criteria are those in your contract and specification.
05How we support buyers of powder coating parts
Coating, Painting and Galvanizing InspectionSurface preparation, paint application, DFT, adhesion and hot-dip galvanizing inspection against the coating specification.
Independent Quality ControlIncoming, in-process and final quality control performed independently at the supplier, with measured results and clear acceptance decisions.