Powder Coating

Powder coating is by far the youngest of the surface finishing techniques in common use today. It was first use in Australia about 1967.

Powder Coating is the technique of applying dry paint to a part. The final cured coating is the same as a 2-pack wet paint. In normal wet painting such as house paints, the solids are in suspension in a liquid carrier, which must evaporate before the solid paint coating is produced.

In powder coating, the powdered paint may be applied by either of two techniques.

The item is lowered into a fluidized bed of the powder, which may or may not be electrostatically charged, or The powder paint is electrostatically charged and sprayed onto the part.The part is then placed in an oven and the powder particles melt and coalesce to form a continuous film.

There are two main types of powder available to the surface finisher:

Thermoplastic powder that will remelt when heated, and Thermosetting powder that will not remelt upon reheating. During the curing process (in the oven) a chemical cross-linking reaction is triggered at the curing temperature and it is this chemical reaction which givens the powder coating many of its desirable properties.

Powder coat produces a high specification coating which is relatively hard, abrasion resistant (depending on the specification) and tough thin powder coating can be bent but this is not recommended for exterior applications.

The choice of colours and finished is almost limitless, if you have the time and money to have the powder produced by the powder manufacturer.

Powder coating can be applied over a wide range of thickness. The new Australian Standard, AS/NZS 4506 – Thermost powder coatings”, will recommend 25 micron minimum for mild interior applications and up to 60 micron minimum for exterior applications.

Care must be exercised when quoting minimum thickness because some powder will not give “coverage” below 60 or even 90 micron. “Coverage” is the ability to cover the colour of the mental with the powder. Some of the white colours require about 75 micron to give full “coverage”. One of the orange colours must be applied at 90 micron.