What is Powder Coating?
Powder coating is a type of coating that is applied as a free-flowing, dry powder. The main difference between aconventional 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 may be a thermoplastic or a thermoset polymer. It is usually used to create a hard finish that is tougher than conventional paint. Powder coating is mainly used for coating of metals, such as household appliances, aluminum extrusions, drum hardware and automobile and bicycle parts.
Removal of oil, dirt, lubrication greases, metal oxides, welding scale etc. is essential prior to the powder coating process.It can be done by a variety of chemical and mechanical methods. The selection of the method depends on the size and the material of the part to be powder coated, the type of impurities to be removed and the performance requirement of the finished product. A common method of preparing the surface prior to coating is known as sandblasting.
The most common way of applying the powder coating to metal objects is to spray the powder using an electrostatic gun. The gun imparts a positive electric charge to the powder, which is then sprayed towards the grounded object by mechanical or compressed air spraying and then accelerated toward the workpiece by the powerful electrostatic charge. The object is then heated, and the powder melts into a uniform film, and is then cooled to form a hard coating.
Once the part is completely coated it is placed in an oven which heats the coating to a minimum of 160 degrees Celsius. Once the powder reaches this temperature it melts and flows together, forming long chemical chains which give the coating its rigidity and durability. As it cools, the surface of the finish takes on a gel-like consistency until it reaches room temperature and is completely cured. Most powder coating finishes will not melt again once they have cured, meaning that they can be used in a wide range of applications and environments without cause for concern.
Advantages of Powder Coating
- Powder coatings contain no solvents and release little or no amount of Volatile Organic Compounds (VOC) into the atmosphere
- Powder coatings can produce much thicker coatings than conventional liquid coatings without running or sagging, to stand up to industrial applications
- Powder coated items generally have fewer appearance differences between horizontally coated surfaces and vertically coated surfaces than liquid coated items
- It offers a wide range of color and finish options ranging from glossy to matte
- It's a viable way to finish and protect parts made from nearly any material, and is suitable even in harsh environments where it may come in contact with chemicals or solvents
- It provides a more durable finish that is both corrosion and scratch resistant so your coating will last for years to come
- It can be easily cleaned with warm soapy water and restored to its original shine within minutes
- Curing time is significantly faster with powder coating as compared to liquid coating