Powder coating is a substitute for traditional wet painting used for automotive and other metallic materials. It is a process of application of a layer of specially treated solid pigment in form of a dry powder to a surface. Heat is then applied to the surface causing it to under go a chemical reaction as the temperature goes up. Consequent upon the chemical reaction, the powder melts and re-solidifies into a single solid surface that matches the contours of the item that is being coated. Powder coating has more advantage over wet painting as it is cheaper, more ecologically friendly and creates a much more durable surface that is less possible to scratch.
The material to be coated must be clean and free of dirt, grease or oil, before being coated. The material is then connected to an industrial winch and sandblasted or dipped in an acid bath. The surface should then be brushed free of any pebbles or dried so that any remaining moisture will be eliminated. It is then connected to a small electrode, giving off a mild positive electrical charge.
The spraying mechanism, which is like a paint gun, is referred to as gun. It is an uncomplicated air-powered device with a hopper consisting of the powdered pigment in form of a polymer. When the powder is fired out of the nozzle, the gun gives off a mild negative electrical charge. This indicates that the powder and material have opposite charges and these opposite charges will attract each other in order for the powder to naturally adhere to the surface immediately upon contact.
Moreover, the powder coating changes at molecular level, forming molecular bonds with every surrounding particle in order to create a flawless shell around the material. As the polymer gets heated, part of it burns and this is not usually seen and does not produce any noticeable gas or smoke. The burning reduces the number of powder particles whereby a little surplus carbon is left behind. The remaining particles form bonds with the surplus carbon and they link with one another in a lattice-like structure. The shell is given the opportunity to cool for some minutes and it is then removed.
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