Paint Finishes
Powder Coating
Powder coating is a type of coating that is applied as a free-flowing, dry powder. The main difference between a conventional liquid paint and a powder coating is that the powder coating does not require a solvent to keep the binder and filler parts in a liquid suspension form. The coating is typically applied electrostatically and is then cured under heat to allow it to flow and form a "skin". The powder may be a thermoplastic or a thermoset polymer. It is usually used to create a hard finish that is tougher than conventional paint. Powder coating is mainly used for coating of metals, such as aluminum extrusions, automobile, and bicycle parts.
While powder coatings have many advantages over other coating processes, there are some disadvantages to the technology. While it is relatively easy to apply thick coatings which have smooth, texture-free surfaces, it is not as easy to apply smooth thin films. As the film thickness is reduced, the film becomes more and more orange peeled in texture due to the particle size and glass transition temperature of the powder. Also powder coatings will break down when exposed to UV rays between 5 to 10 years.
Powder coating finishes tend to crack due to temperature changes. This will result in water seeping under the paint finish allowing it to peel or lift prematurely.
Powder Coating is NOT recommended for Coastal Applications
Baked Enamel
Enamel may be transparent or opaque when fired; baked enamel can be applied to most metals. The great majority of modern industrial enamel is applied to steel in which the carbon is controlled to prevent reactions at the firing temperatures. Enamel can also be applied to copper, aluminum, stainless steel, cast iron or hot rolled steel, as well as gold and silver.
Baked enamel has many excellent properties: it is smooth, hard, chemically resistant, durable, long-lasting color, and easy-to-clean. Enamel is glass, not paint, so it does not fade with UV light. Its disadvantages are its tendency to crack or shatter when the substrate is stressed or bent, but modern enamels are chip and impact resistant because of good thickness control and thermal expansions.
Kynar
¢PVDF is a specialty plastic material in the fluoropolymer family; it is used generally in applications requiring the highest purity, strength, and resistance to solvents, acids, bases and heat and low smoke generation. Compared to other fluoropolymers, it has an easier melt process because of its relatively low melting point of around 177 °C.
¢It has a low density (1.78) and low cost compared to the other fluoropolymers. It is available as piping products, sheet, tubing, films, plate and an insulator for premium wire. It can be injected, molded or welded and is commonly used in the chemical, semiconductor, medical and defense industries, as well as in lithium ion batteries. It is also available as a crosslinked closed cell foam, used increasingly in aviation and aerospace applications.
¢A fine powder grade, KYNAR 500 PVDF or HYLAR 5000 PVDF, is also used as the principal ingredient of high-end paints for metals. These PVDF paints have extremely good gloss and color retention. Kynar paint is the primary choice of architects for applications in coastal areas due to its lower susceptibility to corrosive ocean environments.
Anodizing
Anodizing is an electrochemical process that thickens and toughens the naturally occurring protective oxide. The resulting finish, is the second hardest known substance (diamond being the first). Anodiodic coating is part of the metal, but has a porous structure which allows secondary infusions, (i.e. organic and inorganic coloring).
White the chemical anodizing process remains the same for all applications the mechanical methods vary accoring to the two physical types and shapes of meals used:
1-Batch Anodizing: Parts are racked and immersed in treatment tanks.
2-Continuous Coil Anodizing: Involves continuous unwinding of pre-rolled coils through a series of anodizing, etching, and cleaning tanks, and then rewinding for shipment and fabrication.
Anodizing offers strength, color durability, low maintenance, and eco-friendly processing.