Coating is the process of applying a covering to the surface of an object, typically referred to as the substrate. The purpose of the coating is usually to provide a barrier between the object and the environment and may be merely decorative, like changing the color, or functional, like preventing corrosion, or both. The coating itself may be an all-over coating, meaning it completely covers the substrate, or it may only cover parts of the substrate. Some coatings are used to change the surface properties of the substrate or completely add a new property to the substrate to form an essential part of the finished product.
Classes of coatings used:
- Organic (conventional paints and lacquers)
- Inorganic (porcelain enamel and anodizing)
- Metallic (electroplating and hot-dip galvanizing)
One of the most common forms of coating is wet painting. This is accomplished by cleaning an object before wet spraying liquid paint to an even thickness of approximately 15 - 20 micrometers. The wet paint is applied until the product is evenly coated with the desired thickness of paint.
A specialized form of coating is powder coating, which is applied as a free-flowing, dry powder. Unlike conventional liquid paint which is delivered via an evaporating solvent, powder coating is typically applied electrostatically, and then cured under heat. The powder being used may be a thermoplastic, or a thermoset polymer.
It is used to create a hard finish that is tougher than conventional paint. Powder Coating is typically used on metals such as:
- Aluminum Extrusions
- Drum Hardware
- Automobile Components
- Bicycle Parts