Architectural coatings provide improved aesthetics and critical substrate protection. They are formulated to meet many key coatings properties such as opacity, stain and dirt pickup resistance, washability, weatherability, adhesion or cracking resistance, to name a few. Unfortunately, despite optimising the paint for these and other variables, unexpected failures may still occur after paint application, drying and aging. The 'snail trail' phenomenon is one such failure, which we discuss in detail in this article. Snail trail is often described as a change of appearance that happens over the first days or weeks of exposure to ...