What Does Flaking Resistance Mean?
Flaking resistance is the prevention of a type of paint failure or the methods adopted to prevent the detachment of coating or paint fragments from the substrate's surface. In flaking, the paint lifts up and peels away from the substrate due to a loss of adhesion. Flaking is the most likely result when paint is applied over a moist, greasy, chalky or otherwise improperly prepared surface. Flaking causes paint failures, which lead to corrosion of the substrate.
The causes of flaking include:
- Poor-quality paints that possess poor adhesion and flexibility.
- Improper surface preparation.
- The paint coating layer is too thin.
Corrosionpedia Explains Flaking Resistance
Flaking is a condition of paint failure where tiny pieces of coating lift up from the surface of the substrate. Flaking is commonly seen on wooden surfaces (e.g., fences and old wooden buildings). It can also occur on metal surfaces, especially galvanized surfaces.
Flaking usually begin with thin, hairline cracks in the paint film that grow with time. Flaking is caused by decomposing paint and is different from efflorescence or mottling, which display white, crusty mineral salt deposits that have leached from mortar, concrete or masonry surfaces behind the paint. Rust usually appears as orange flaking on a surface.
As alkyds or oil-type paints applied on galvanized surfaces age, they oxidize to the point where the paint film shrinks and pulls itself away from the surface. Here, an interfacial chemical reaction also occurs, which creates a zinc soap between the organic coating and the zinc substrate. This ultimately causes adhesion loss of the coating substrate, as well as flaking.
Flaking can be prevented by properly cleaning the surface and by using a coating that possesses strong adhesion and good aging characteristics.