A crack can be ordinary, unexceptional, something to be accepted as merely ‘patina of age’. Cracks reflect the biography of a painting as of a face. Like a wrinkle, a crack is a gentle reminder of the vicissitudes of age and repeated small actions which accumulate over time. Or it can be a frightening glimpse of further structural breakdown, of chemical incompatibilities, of tensions below the surface hidden to the eye.

A crack in a painting always represents some form of ‘release’, where a new mechanical equilibrium is achieved and where tensions relax. Conservators group cracks into two categories, mechanical cracks and drying cracks. Mechanical cracks are those where the paint has sharp broken edges, caused by either stress within the painting as it responds to environmental fluctuations – swelling and shrinking, impact or vibration. These types of cracks can be described as concentric, conchoidal, sigmoid, fractal, fissured or feathering. They may twist and change direction, make garlanding patterns around the edges of an artwork, sprout barbs and form a dead end. They can run parallel, bisect a corner or cross hatch like a draftsman’s pen. The very descriptive nomenclature used by conservators is something visual and almost poetic.