Cusping

A series of regularly spaced scalloped or wave-like distortions visible along the edges of a canvas painting. Cusping is typically caused by the original stretching of the canvas over a stretcher or strainer, where tension is applied unevenly between tacking points. These distortions are often considered inherent to the painting’s original preparation rather than later damage, although changes in humidity, re-stretching, or lining can make them more pronounced or alter their appearance.