Powder Coating.... So why is it good for my stuff?



    We have had several conversations recently about the benefits of powder coating vs painting. What exactly is powder coating? And why is it more durable and longer lasting than paint?

The material that most powder is made from is basically “plastic”. Polyesters are chemically related to plastic and have an extremely strong chemical bond. Some may remember the wonderful but hideous polyesters of the 1970s. While some inexpensive polyesters and plastics are rigid and brittle, there are many forms of plastic such as kevlar, nylon and plexiglass that are strong and flexible. The molecular bonds that make plastics so durable also make them extremely resistant to the natural process of decomposition. This is one reason why powder coating is so long lasting.

Most quality powders are made from pure or blended polyester resins. These start out in liquid form and are poured into molds to dry. Imagine a huge ice cube tray. Then the blocks of dried resin are ground into a fine powder by a giant blender. Different colors can be made by mixing pigment during the liquid resin stage or by mixing powders. The multitude of chemistries make powder mixing somewhat dicey. The various chemistries in different powders and metal flakes repel each other and create vein and hammertone effects. Textured powders are made by mixing powders of different chemistries after they are ground.

When powder is applied to metal and placed into the oven for cure, it melts together to form a continuous and resilient seal against moisture, rust and corrosion. Unlike paint, powder does not contain chemicals that evaporate during cure -once powder is cured in the oven, it remains flexible. Because it is in the plastic family, powder continues to move with the metal as it expands and contracts with the weather. Paint gets harder as the chemicals that make it liquid evaporate. Once paint cures, it is more likely to chip, crack and peel, allowing the metal underneath to rust. Because of it’s plastic nature and flexibility powder bounces back instead of chipping.

Almost all powder contains UV protectants that help maintain both color and gloss throughout the years. While most paint begins to fade after 1-2 years, powder will stay glossy for 10-15 years or more. We have attached a picture of two trellises that were installed in mid 2007. One was painted (not by Z shop) and is on the “protected” side of the building. It receives morning sun. The other was powder coated (by Z shop) and receives full afternoon sun. While the painted trellis is faded, chipping and rusting, the powder coated trellis still looks as good as day one. If you would like to see them, give us a call and we can tell you where they are located.