A powder coating finish is one of the most preferred finishes by manufacturers as well as consumers mainly due to its high quality, resistance to corrosion and durability.
Irrespective of the above qualities, a powder coating finish is prone to getting defects that are a result of contamination by various environmental conditions as well as elements present in the coating booth. It is essential to note that the contamination can take place anywhere in between the preparation of the powder coating to its application on a product. Hence, due diligence is recommended throughout the process to ensure you get a high-quality powder coating finish.
Ensure that the substrate is contaminant-free before applying the powder coating
The first chance you get to contain any chances of powder coating contamination is in the pre-treatment process of the substrate. However, it is essential to realize that in most cases the method of pre-treatment entirely depends on the specified requirements necessary for the product's coating.
Hence, it is mandatory that a spray washer paired with an alkaline cleaner is utilized to remove any traces of organic dirt waxes as well as rust inhibitors from the substrate to ensure it is contaminant-free before powder coating gets applied. The primary purpose of the cleaning process here is to eliminate all traces of impurities that could hinder the adherence of the powder coating finish to the surface of the product.
Use a drying oven to remove all traces of water after cleaning
Washing the substrate removes impurities with the potential of contaminating the powder coating finish; however, traces of water left behind after the washing process also have the ability to cause blemishes or unevenly coated areas on the surface of the product.
Hence, after the washing, it is extremely crucial that the substrate gets placed in a drying oven and heated to above the boiling point of water (preferably at 110° Celsius) to remove any traces of water from the surface.
Regulate the humidity level of the workshop
Despite moisture being considered irrelevant by some manufacturers, it can affect the powder coating finish because coating powder is very sensitive to moisture.
Hence, if the moisture content in the air is high enough, it can lead to the agglomeration of coating powder which affects the fluidity of the powder coating during application. On the other hand, if the powder clumps up, it can damage the spray gun. So before preparing the coating powder or applying it, it is recommended that the humidity levels in the coating booth do not exceed 50%.
Implement the powder coating at recommended temperatures
Additionally, the application of powder coating is sensitive to heat. Warm temperatures facilitate the adherence of powder coating finish to the surface of a product. Nonetheless, if the temperature is too high, the particles will melt on the product's surface and cause the formation of tacky patches.
Note. If you apply more coating to a tacky patch, it will result in the formation of a bump defect. So before commencing the powder coating application, ensure the surface of the product is at the right temperature; typically between 25° and 30° Celsius.