Painting helped co-ordinate the windows with the rest of the home or structure. It also took the market from "anodizing only" for the very high-end architectural and commercial uses and created new and more vibrant looks.

As this momentum continued, improvements like double panel, thermally separated glass came along for better insulative properties. Innovative curtainwall designs emerged as did new and improved residential glass enclosures. It ushered in a new era in the aluminum extrusion industry that is far from over.

There are two methods of spraying coatings on aluminum extrusions: Horizontal and Vertical.

HORIZONTAL

This method is usually preferred for coating complex panels that cannot be hung on a vertical line such as, louvers and prefabricated systems. The typical layout begins with hanging the aluminum component on specially designed racks or hangers, then onto a conveyorized line. From the loading area it travels through a cleaning and pretreatment process that removes the soils and dirt from the substrate. It also puts an approved chemical treatment, chrome or (non-chrome in some instances), on the metal to promote adhesion of the paint and deter the formation of salts or corrosion. On some lines this is done as part of the process on-line and in some cases it is done off-line with the same basic chemicals only applied by dipping or immersion in a multi-stage process. Following this key step, the metal is ready for painting. Normally three sets of opposing booths are in place to apply primer, topcoat and clear if specified for architectural finishing. Horizontal application typically uses a combination of manual and automatic electrostatic equipment.

VERTICAL

This describes the way the metal is hung during the pretreatment and painting processes. Usually long runs of extrusions are coated with either one or two pairs of opposing omega-shaped booths that are on average more than twenty feet tall. These are strictly automatic, electrostatic rotary systems, capable of faster line speeds and more volume. High volume producers that extrude and paint usually employ this Vertical method. All other steps are basically the same as with the Horizontal method. Both types of lines are either currently incinerating the VOC's or are in the planning process of reducing overall VOC emissions.