Liquid painting and powder coating are two techniques used in industrial finishing. Both typicallyr require a heat curing process, but they differ greatly in their methods of application. Liquid painting is the standard method employed for coating. With recent changes in finishing technology, powder coating is the latest popular option used for different substrates.
Painting involves the spreading of liquid paint over the product surface. It consists of a single component that dries when exposed to air or UV light. The powder coating process uses dry, free flowing powder. A spray gun spreads the powder electrostatically on the surface. It’s then exposed to high temperature, which bakes the surface and melts the powder to create a smooth, solid layer.
Painting colors a surface aesthetically and produces a smooth, shiny surface. It can easily peel off when scratched with a sharp object. It chips and fades faster allowing the product to rust. Powder coating is seamless on the surface, which protects the exterior from corrosion and other spoilage. It is fade, chip and peel resistant. It is cheaper than spray paint, and can last up to 20 years.
Liquid paints have chemical cross linking which cures at a higher temperature. Those paints that have catalysts need moisture or room temperature curing. Regardless of the curing method, solvents evaporate during the curing process. High temperature curing requires about 15 to 20 minutes of baking at 170 to 180 degrees Celsius. Cure time for powder coating depends on the product surface and the powder. Powder begins to melt and spreads out when exposed to high temperature. Powders cure at temperatures around at 200 degrees Celsius in 10 to 15 minutes.
Liquid paints emit volatile organic compounds that endanger the environment. They produce more waste than powder coating. Unlike liquid painting, powder coating has zero impact on the environment because it is free of solvents. Reuse and recycling of excess powder achieves 100 percent usability. Unlike liquid paint, powder coating does not release carcinogens.
Liquid paints are useful when working on products that have small tolerances. Specialized gloss and metallic colors are available in liquid paint that are difficult to match with powder. Liquid paints are convenient to use for smaller quantities of products that run in batches. Liquid paints are used on plastic, since it cannot withstand high temperature. Powder coating produces thicker finishes.