Wet Paint Finishes on Aluminum Extrusion Products


Among the many finishing options available for aluminum extrusion products, wet paint finishes are a versatile choice, offering more colors than any other process. There are a number of reasons to choose a wet paint finish over anodizing or powder coating finishes.

Selecting a particular type of finish depends on several factors, including the final appearance you want to achieve, where and how the product will be used, and if you intend for the finish to function primarily as a protective measure. If the goal includes a combination of protective and aesthetic considerations, then a decision needs to be made on the relative importance of these factors when selecting a finish.

Wet Paint Finishing Process
Paints used as liquid coating for aluminum extrusion products encompass different types such as acrylics, fluoropolymers, polyesters, and siliconized polyesters. Each coating contains pigments and resins, or binders, which are the primary basis for their classification.

Wet paint finishes on aluminum extrusion products must undergo an initial pre-treatment process. This is done to remove the black or grayish smut, which is the initial stage of oxidation that develops when the newly processed extrusion surface is exposed to oxygen. If this cleaning is not performed, the paint sticks to the smut, and could later flake off. This pre-treatment varies from a degreasing spray of tricoethylene to the spraying of a zinc chromate primer.

The next stage is the application of the paint, which is most often performed manually. The sprayer studies the die drawings to apply the paint to the object accurately, thus the final finish is dependent on both the specifications and the expertise of the sprayer. These wet painted extruded products are cured or baked in order to dry and harden the new finish.

Finishing facilities, like the one at Spectra Aluminum Products, incorporate the latest technology, making them energy efficient with minimal maintenance requirements. Most consist of a vertical wet line, which uses conveyors to help move the extrusions. These products can reach lengths of 20-25 feet. The facilities also include pretreatment chambers, spray paint booths, convection ovens, unloading zones, and Volatile Organic Compound (VOC) emission control systems.

Benefits of Wet Paint Spray Finish
In addition to the wide range of colour choices, the benefits of wet paint finishes for aluminum extrusion products are as follows:

  • Wet paint finishes are smoother than powder coating.

  • They provide excellent protection against corrosion when exposed to the elements.

  • Liquid coatings exhibit better bright metallic colors.

Some examples of aluminum extrusion products that use wet paint finishes are window frames, exterior cladding, playground equipment, flagpoles, curtain walls, stairway railings, and many others.