Powder coating is an advanced method of applying a decorative and protective finish to a wide range of materials and products that are used by both industries and consumers. The powder used for the process is a mixture of finely ground particles of pigment and resin, which is sprayed onto a surface to be coated. The charged powder particles adhere to the electrically grounded surfaces until heated and are fused into a smooth coating in a curing oven. The result is a uniform, durable, high-quality, and attractive finish.
Powder coating is mainly used for coating of metals, such as household appliances, aluminum extrusions, drum hardware and automobile and bicycle parts. Newer technologies allow other materials, such as MDF (medium-density fibreboard), to be powder coated using different methods.
The fundamental distinction between a regular fluid paint and a powder coating is that the powder coating does not require a dissolvable to keep the fastener and filler parts in a fluid suspension shape. The coating is ordinarily connected electrostatically and is then cured in an oven. It is generally used to make a hard finish that is more durable than ordinary paint.
Powder coating does not have a liquid carrier and thus produces thicker coatings without running or sagging, and powder coating produces minimal appearance differences between horizontally coated surfaces and vertically coated surfaces. As no carrier fluid evaporates away, the coating process emits few volatile organic compounds (VOC).
Pretreatment is a necessary process in the case of powder coating. Here this is mainly concerned with metals as powder coating is predominantly applied to metals. The pretreatment process depends on the metal that is being treated as well. The various surface preparation processes include: Cleaning (mechanical or chemical), Conversion Coating Application.
Mechanical cleaning includes methods like scratch brushing and sand blasting. This by abrasive action not only removes the surface impurities but also eliminates scratches and surface irregularities. Cleaning is very good, however, coating must be done immediately because the cleaned surface is in a highly reactive state and corrosion occurs very soon.
Chemical cleaning includes removal of dirt, oil and grease, and the oxidation products present on the surface by means of chemicals. The chemicals may be applied by wiping, spraying or dipping.
Powder coatings contain no solvents and release little or no amount of Volatile Organic Compounds (VOC) into the atmosphere. Thus, there is no longer a need for finishers to buy costly pollution control equipment. Companies can comply more easily and economically with the regulations of the U.S. Environmental Protection Agency.
Powder coatings can produce much thicker coatings than conventional liquid coatings without running or sagging.
Powder coated items generally have fewer appearance differences between horizontally coated surfaces and vertically coated surfaces than liquid coated items.
The wide range of specialty effects are easily accomplished using powder coatings that would be impossible to achieve with other coating processes.
Curing time is significantly faster with powder coating as compared to liquid coating.