Liquid paint is composed of pigment, resin, and solvent. Powder paint is simply pigment encapsulated in a powdered resin and is thus simply thought of as “Paint without the solvent.” Powder coatings and liquid coatings made from the same resin and pigment will have practically the same performance characteristics. For a given resin, the decision to use a powder or liquid coating is mainly a question of application technique.
The real advantage of powder is the reduction in air pollution compared to liquid coatings. When powders are cured in an oven they emit no VOCs. A disadvantage of powder is the large batch sizes that are typically required. The powder manufacturers are aware of this problem and a few of them keep colors in stock that they distribute in small batches. Several companies manufacture exterior grade powders using a Polyester TGIC resin. Polyester TGIC powders are currently available in more stock colors than any other powder. Several companies stock hundreds of colors of Polyester TGIC powders. Polyester TGIC struggle with gloss retention compared to PVDF powders, but are widely used in Europe.
Some resins are more easily manufactured in liquid coatings and some are more easily manufactured in powder coatings. A particular resin is usually manufactured in either powder or solvent based coatings, but not both. Examples of this are epoxy which is predominantly a powder coating, and PVDF which historically has been manufactured as a liquid coating. Many of the perceived advantages of powders over liquid coatings such as hardness and gloss are actually characteristics of the resin.
Powder coatings from most manufacturers are only available in large batches and custom colors can be very expensive. This is because each batch of powder must be ground to order using costly grinding equipment. Solvent born colors will continue to maintain their niche in the market because of the ease with which small batches can be mixed.
The ability to “mix and match” gives painters and their customers unequalled flexibility and ease of use.
During the last ten years PPG, Akzo and others have introduced AAMA 2605 fluorocarbon-based powder coatings. Most of these are based on FEVE resins which are superior to Polyester coatings. PPG has introduced the PVDF Duranar powder which offers not only AAMA 2605 performance, it is also practically identical in appearance to liquid PVDF coatings. We expect the use AAMA 2605 powder coatings to increase.
Galin also applies epoxy based powders for interior applications such as furniture. One note of caution about powders: they are prone to orange peel and the coating may appear to be textured.