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Powder, Liquid or Pre-Painted

Which technology should you choose?

Azko Nobel March18 1

With technologies and products evolving at a rapid rate, choosing between different building finishes may at first seem daunting.

However, it is important to understand that the two main categories of coatings—liquid and powder—are, in fact, not that different at all. The main distinction between liquid and powder coatings is their application process and not their chemistry or performance.

Application method

Deciding what application method to use depends largely on an individual project’s circumstances, such as what climate the building is located in and what kind of durability is needed in the finish. To achieve the desired performance level in a given situation, coatings must be specified to meet third-party industry standards. The American Architectural Manufacturers Association (AAMA) is the most commonly referenced quality organization. AAMA offers voluntary specifications, performance requirements and test procedures for pigmented organic coatings on aluminum extrusions and panels. It recognizes three levels of performance, often referred to as standard-, super- and hyper-durable (AAMA 2603, 2604 and 2605 respectively). Coatings meeting the AAMA 2605 standard are appropriate for use on high-end building exteriors and are expected to last the lifetime of the building.

Many tests are required during a coating's research and development, but the performance test that is of most concern to the end user is weatherability, particularly UV resistance. Tests that are specific to weatherability measure a coating’s color retention (also known as fade), chalk resistance and gloss retention.

Data from weather testing performed south of latitude 27 degrees north (at facilities in South Florida) is considered to be the global "gold standard" of testing data. Florida offers high annual UV exposure, high year-round temperatures, abundant rainfall and very high humidity. The subtropical climate in that region provides natural, realistic exposure to product specimens, yet results can be achieved on an accelerated timeline because one year of Florida’s sunshine and moisture is comparable to two or more years of exposure in other regions. A south-facing rack mounting, with test panels positioned at a 45-degree angle, also makes exposure conditions more severe. Because of the harsh testing conditions, a 10-year South Florida rating is likely to correspond to 23-25 years of real-world performance (where climates are milder and installation of cladding is vertical).

Whether liquid or powder, coatings are comprised of two principal ingredients: resin and pigment. Resin is the most important part of a coating; it binds the coating to the substrate, providing weather resistance and durability. Resin also provides the coating’s resistance to abrasion, scratching and dirt accumulation. Resins used to define paint include:
• Fluoropolymers
• Silicone-modified polyesters
• Super durable polyesters
• Polyester
• Urethane
• Acrylic
• Epoxy

Fluoropolymer resins are the most widely known resin types available to the fenestration industry. They include polyvinylidene fluoride (PVDF) and fluoroethylene vinyl ether (FEVE). Fluoropolymer resins are high performers for exterior weatherability and UV stability in both powder and liquid coatings. Fluoropolymer powder coatings are purposely tailored for the architectural market and offer a long-life, durable finish.


The second-most important part of a coating is its pigment. Pigments are generally organic (with carbon-containing molecules) or inorganic (e.g., ceramic and silica). They provide color and coverage as well as enhance certain physical properties of the coating. Each has particular qualities. 

Organic pigments, for example, can achieve bright saturated appearances; whereas ceramic pigments provide lasting durability, and silica affects gloss. Inorganics, made from metal oxides, have superior color stability and chemical resistance. They are not, however, available in all colors, and sometimes both pigment types are used to achieve a certain color. The selection of pigments is based on physical needs as well as requirements for durability, gloss, color fastness and chemical exposure.

Both liquid and powder coatings can be applied using a hand spray method or automatic spray equipment. Automated coating processes use electrostatic attraction: the powder particles or liquid droplets are positively charged, causing them to be attracted to the grounded or negatively charged metal. Metal coil (typically aluminum, galvanized metal or zinc/aluminum coated steel) is coated—usually with liquid paint—in a highspeed, controlled factory setting. Pre-painted coil can be used to construct architectural cladding panels as it is a cost-effective way to coat large flat surfaces that can then be formed into many shapes as the project requires. It is also a common choice for metal roofing. Liquid and powder coatings each have their own strengths, but they are not always interchangeable.

When choosing a paint type, it is important to understand which applications are most appropriate for a given building envelope, and what will perform best for an individual project or market.

Ben Mitchell, MBA, is sales manager of extrusion coatings at AkzoNobel, Columbus, Ohio. To learn more, visit