What is a common cause of filliform corrosion?

Filliform corrosion is specifically associated with the presence of moisture and contaminants under a paint film, particularly on aluminum surfaces. A common cause of this type of corrosion is the improper or incomplete curing of a wash primer prior to painting. When a wash primer is not cured properly, it may retain moisture or other contaminants beneath the paint layer. This creates an environment conducive to corrosion, as the moisture can react with the aluminum, leading to the formation of corrosion along the interface between the primer and the substrate.

The curing process is critical because it allows the primer to bond effectively to the metal surface, preventing moisture and other elements from seeping in. If this step is overlooked, the protective layer becomes compromised, and filliform corrosion can develop over time as moisture is trapped and begins to react with the metal.

In contrast, while alcohol contamination, excessive heat application, and exposure to UV light can contribute to various forms of material degradation or corrosion, they are not directly linked to the specific mechanism of filliform corrosion in the same manner as improper curing of a wash primer. Each of these factors may affect the integrity of coatings or materials in different ways but do not create the ideal conditions for filliform corrosion to occur.