Powder coating, as the name signifies, is a technique of using dry powder for surface finishing. It is relatively a new way of surface coating as compared to other methods. It was believed to have been implemented for the first time during 1967 in Australia. It can be used for finishing any surface, provided that the material to be coated should be able to withstand the elevated curing temperature.
The actual process is not as difficult as it sounds. In fact, its popularity is contributed mainly due to the ease of application and smooth texture of the finished surface. With the right equipment, it can be performed easily by following some basic tips.
Equipment: Powder coating electrostatic guns and electrostatic tunnels are used to apply coat to the surface. There are several types of electrostatic guns, some of which include turbo charging guns, corona charging guns, and bell charging guns. While carrying out the coating, powder of a specific color and quality, is fed into the gun or tunnel, which is then charged and sprayed on the surface. The charging mechanism varies from one equipment to another.
Types of Powder: A free-flow, dry powder, used in coating consists of a mixture of resin, pigments, and hardener. The mixture is treated in certain steps to create a fine form. There are two main types - thermoplastic and thermosetting. The former melts at a high temperature, which is responsible for adherence to the material. In case of thermosetting, it reacts with other ingredients during baking, which increases its adhesive property.
Process: The process can be carried out in three common steps, namely, pre-treatment of the surface to be coated, application of the powder, and curing the surface. First of all, the surface (metal or fire board) to be treated is prepared by cleaning dust, dirt, or other contaminants. Following this, dry powder is applied electrostatically on the pre-treated surface. The coated surface is then cured by exposing to an elevated temperature (more than 200 degrees Celsius), either in a convection oven or a infrared oven for about 10-15 minutes.
Industrial Application: The large metallic products, whether aluminum, iron, or steel, are treated to give a smooth finish texture or a wrinkled appearance. There are industrial services that take the orders on a large-scale. The color, texture, and powder type applied on the surface, are variable as per the requirements of the customer.
Powder coating has become very popular for finishing cookware, automobile parts, gokart parts, and other household items. Unlike wet painting that releases certain volatile chemical compounds, it is considered as an environment friendly procedure for surface finishing. The leftovers after the completion of the process can be collected easily and used again for further application.