Which factor can cause alligatoring in thickly applied coatings?

Alligatoring in thickly applied coatings is primarily caused by prolonged exposure to sunlight. This phenomenon occurs when a coating material experiences degradation due to ultraviolet (UV) radiation. When coatings are excessively thick, they can trap solvents and moisture within the layers. Over time, exposure to sunlight increases the temperature of these layers, causing the trapped solvents to evaporate and the top layers to dry out faster than the underlying layers.

As the top layer contracts, it can lead to the formation of cracks that resemble the skin of an alligator. This failure mode highlights the importance of following proper application thickness guidelines and ensuring adequate curing conditions. Using lighter, more UV-resistant materials can help mitigate this issue.

Humidity, temperature, and material quality can influence coating performance, but they do not directly lead to the specific cracking pattern associated with alligatoring as prolonged sunlight exposure does.