Plastic coating is the process of applying a thermoplastic to the surface of metal items to provide long-term corrosion, impact and chemical resistance whilst offering an attractive decorative finish. Plastics tend to be applied a little thicker than standard paints and are generally impermeable to water or aggressive chemicals. As a result thermoplastics are ideal for very long term protection of metal in the construction and automotive industries or for the coating of welded items such as wire baskets, fencing mesh and cylinders.
The materials are supplied in powder (or liquid) form and are usually applied in the factory by standard fluid-bed (fluidised bed) or electrostatic spray techniques.
Thermoplastic powders can be coated using either the fluidised bed dip coating process or by electrostatic spraying. The advantages and disadvantages of each process are summarised below.
Fluidised Bed Coating: - 100% coating efficiency,
- Faster cycle times,
- Thicker coating providing: functional protection, longer life, impact resistance but with higher material usage,
- Superior edge coverage,
- Requires fluidised bed to be full of powder,
Electrostatic spraying: - Freely available sources of spray equipment,
- Thinner coatings,
- Lower material usage,
- Reduced inventory requirement,
- Lower coating efficiency (depending on the article and reclaim facilities).
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