Affording very attractive finishes to products and components, powder coatings provide a durable and protective layer which can help to prevent structural damage, corrosion and cosmetic problems, such as scratching or fading. Like other protective coatings, the process of applying them is often conducted by specialist contractors. In the case of powder coating, a procedure of electrostatic spray deposition, or ESD, is frequently adopted to achieve a thorough application. How is this done and what are its effects?
Powder Coating Spray Application
A powder coating is based on a polymer resin which has been mixed with curatives, pigments and something the industry refers to as levelling agents, usually provided in the form of solvents. Along with a few other additives, like flow modifiers for certain coating types, the coating's ingredients are melted together then cooled. After this, a spray gun is used to apply the resin mixture to the item it is to cover with an electrostatic charge. Essentially, the powder particles are charged which means they are attracted to the surfaces of the items they are covering and stick on to them evenly.
The Curing Process
After the ESD has applied the polymer resin to the surface of the material being coated, it is necessary to cure the coating to prevent it from being wiped off easily. Curing simply means that the coating hardens and becomes permanent. In the main, this is achieved by placing the entire product into a curing oven where the powder coating is heated up. It is the heat which makes the coating to react chemically which – at a structural level – means that long molecular chains are produced, resulting in a more dense and durable coating. This dry curing process can be switched for a hot bath method using liquids, but this is not widely-used other than for specialist applications.
Benefits of Powder Coatings
As well as a choice of colours that are almost limitless, powder coatings can be used on all sorts of materials. Commonly applied to metal products, such as bollards and road signs, powder coating is equally at home being used with things like MDF. Unlike some paint applications, powder coating creates an even finish which is also hard wearing. Therefore, it is desirable to use on products which will be exposed to the elements or to wear and tear during their daily lives. Powder coatings are resistant to moisture and ultraviolet light as well as being an environmentally responsible choice.