technology for coating products with dry powder rather than conventional liquids
has been available since the 1950s. The powder used for the process is a mixture
of finely ground particles of pigment and polymeric resin. The powder is either
sprayed electrostatically onto a surface to be coated, or the substrate is dipped
into a fluidized bed of suspended powder. The powders adhere to a preheated substrate
surface in the fluidized bed process, or they adhere electrostatically in the spray
process. When heated further in a curing oven, the particles flow and fuse into
a strong, adhering coating. The result is a high quality coating with an attractive
finish and excellent durability.
The growth of powder coatings has been dramatic during the last two decades with
new applications continually being developed for both industrial and consumer related
markets. The growth can be attributed to the powder coating industry meeting customers'
demands with a two-pronged attack:
- The development of new formulations and
- The development of advanced equipment and application processes.
These developments have created many new market opportunities and helped overcome
finishing obstacles that were common in the early days of the powder coating industry.
Powder coating contains no solvent
||Powder coatings have been shown to possess significant durability and resistance
to abrasion, corrosion, scratching, and chemicals when compared to liquid coatings.
Powder coatings stay bright with less fading, and color selection is virtually unlimited
with high and low gloss, metallic, and clear finishes available. Texture selections
range from smooth surfaces to wrinkled or matte finishes, and rough textures are
available for hiding surface imperfections. Thick coatings can be achieved quickly
Although the final properties of the powder coatings are often superior to liquid
coating systems, the reason for the fast growth of this technology has been more
related to the evidence that powder coatings maximize production, cut costs, improve
efficiencies, and offer maximum compliance with increasing stringent environmental
regulations - factors all related to the end-user's bottom line.
Environmental advantages have led the way for the conversion of liquid coatings
to powder coatings.
, and thereby the process
emits negligible, if any, polluting volatile organic compounds (VOCs) into the atmosphere.
Furthermore, the processes used for powder coating do not require venting, filtering,
or solvent recovery as is necessary with liquid finishing. Costs are saved because
there is less need for heating outside air to supply oven exhaust air, and most
of the powder coating over-spray can be retrieved and re-used.
The table below summarizes the advantages and disadvantages of powder coatings. Recent developments
in materials and process technology have greatly minimized the disadvantages that
are listed here. These developments are summarized in this article.
Powder Coatings Advantages & Disadvantages