Powder coating is a type of coating that is by far the youngest of the surface
finishing techniques in common use today.
It produces a high specification coating
which is relatively hard, abrasion resistant, tough, and can be bent to a certain degree.
The main difference between a conventional liquid paint and a powder coating is that the
powder coating does not require a solvent to keep the binder and filler parts in a liquid suspension form.
The coating is typically applied electrostatically and is then cured under heat to allow it to flow and
form a “skin”. The powder then becomes a hard finish that is tougher than conventional paint.
There are several advantages of powder coating over conventional liquid coatings:
- Powder coatings emit zero or near zero volatile organic compounds (VOC).
- Powder coatings can produce much thicker coatings than conventional liquid coatings without running or sagging.
- Powder coating overspray can be recycled and thus it is possible to achieve nearly 100% use of the coating.
- Powder coating production lines produce less hazardous waste than conventional liquid coatings.
- Powder coated items generally have fewer appearance differences between horizontally coated surfaces and
vertically coated surfaces than liquid coated items.
Many manufacturers actually prefer to have a certain degree of orange peel
since it helps to hide metal defects that have occurred during manufacture,
and the resulting coating is less prone to showing fingerprints.
While powder coatings have many advantages over other coating processes,
there are some disadvantages to the technology. While it is relatively easy
to apply thick coatings which have smooth, texture-free surfaces, it is not
as easy to apply smooth thin films. As the film thickness is reduced, the
film becomes more and more orange peeled in texture due to the particle size
and glass transition temperature (TG) of the powder, also powder coatings
will break down when exposed to UV rays between 5 to 10 years.