Painting is not just about enhancing the appearance of a structure; it also serves as a protective barrier against various damaging elements like corrosion, decay, and weathering. However, the effectiveness of paint can be compromised if not chosen wisely based on factors such as surface type and environmental conditions. This article explores common painting defects that may arise if these considerations are overlooked.
Blistering and peeling occur when the paint film swells due to the presence of moisture, oil, or grease. If caused by moisture, it’s called peeling, and if caused by oil or grease, it’s called blistering. Factors like imperfect seasoning of timber and excessive oil in the final coat contribute to these defects. Using porous paints like emulsion paints can help eliminate these issues.
Fading is the discoloration of the paint surface, mainly caused by atmospheric elements such as sunlight and moisture. To prevent fading, it’s crucial to use weather-resistant pigments in the paint.
Insufficient opacity of the paint film, leading to the visibility of the background surface even after the final coat, is termed grinning. Using opaque paints is essential to address this defect.
Chalking, the formation of powder on the painted surface, results from insufficient oil in the primer. Preventive measures include using adequate oil in the primer and applying paint at the recommended spreading rate.
Running occurs when a thin layer of paint is applied to a glossy and smooth surface, causing the paint to run back and leave small uncovered areas.
Sagging is the downward flow of a thick paint film on a surface, similar to running but with a thicker sag of paint.
Flaking is the detachment of the paint film from the surface due to poor bonding. Proper surface preparation, including cleaning and rubbing with abrasive paper, helps prevent flaking.
Blooming, caused by improper ventilation, weathering, or defective paint, results in dull patches on the painted surface.
Wrinkling occurs when a thick layer of paint shrinks and develops crawls on the surface. Complete drying of the undercoat before applying the final coat can prevent this.
The formation of glossy patches on the painted surface, known as flashing, is caused by poor-quality paint, weathering, or poor workmanship.
Saponification occurs when painted surfaces are exposed to alkalis, leading to the formation of soap patches and peeling of the paint film.
Alligatoring, resembling the scales of an alligator, happens when a hard coat of paint is applied over a soft or existing coat. Using a high-quality oil-based primer as a prime coat can prevent this.
Similar to alligatoring but with cracks limited to a small area, checking occurs in very cold weather or when paint is applied before the undercoat is dry.
Mildew, a fungus thriving in warm, moist, and dark places, causes grey patches on the painted surface. Keeping the surface dry and clean before painting and using a bleach solution for mildew traces can prevent this issue.
