The powder coating process step by step
From dry powder to a hard, uniform surface without solvents
Powder coating is today one of the most common surface treatments in Danish industry — from rims and radiators to steel components of all sizes. The method is popular because it is virtually free of solvents and produces a hard, uniform surface, but the process requires hitting several steps correctly along the way.
§Pre-treatment is still half the work
Regardless of coating method, the same basic principle applies: a greasy or dirty surface gives poor adhesion. The workpiece must therefore be degreased and cleaned thoroughly — and often phosphated — before the powder gets anywhere near it. A perfectly executed powder application can never compensate for poor surface preparation.
§Electrostatic application
The powder is charged electrically as it is blown out through the powder gun. The workpiece is grounded or oppositely charged, so the powder particles are attracted and stick to the surface, almost like a magnet. In deep, internal corners, you may encounter what is called the Faraday cage effect: the electric field is shielded there, making it harder to get the powder to stick evenly.
§Hardening in oven
After application the part is run through a curing oven, typically at a temperature of around 180-200 °C, depending on powder type and the supplier's technical data sheet. Here the powder particles melt together and undergo a chemical cross-linking reaction that binds them to a coherent, hard surface layer.
| Subject | Wet paint (solvent- or water-based) | Powder coating |
|---|---|---|
| Solvents/VOC | Can release solvents into the air | Almost free of solvents |
| Overspray | Rarely possible to recycle | Can often be collected and reused |
| Requirements for the workpiece | Most materials and sizes | Must be electrically conductive and withstand the hardening oven's temperature |
| Typical application | Large, site-bound constructions | Parts that can be run through a pre-treatment and hardening system |
§Advantages and limitations
- 01Advantage: environmentally friendly process without significant VOC emissions
- 02Advantage: wear-resistant uniform finish and possibility of reusing overspray
- 03Limitation: the part must be electrically conductive and withstand the hardening oven temperature
- 04Limitation: poorly suited for very large or site-bound structures that cannot be transported through a plant
Overall, powder coating is a process where the sequence of surface preparation, electrostatic application and curing must be followed carefully — but in return it provides a durable and environmentally friendly surface when the steps are performed correctly.