Craquelure

Craquelure is a network of fine cracks that appears on the surface of paintings, varnishes, or ceramic glazes as a result of aging, drying, and stress in the materials. It can occur in oil and tempera paintings, as well as in the varnish or ground layers, and is also observed in ceramic wares where the glaze develops a crackled pattern. The term craquelure (or craquelé in French) describes the visible crack pattern rather than a single material.

In paintings, craquelure arises mainly from differential shrinkage and contraction between layers during drying and aging. The oil binder, ground, and varnish have different elastic properties and respond differently to temperature, humidity, and light. Over time this creates a reticulated network that can be fine and regular or more irregular. The pattern is influenced by the age, technique, support, and previous restorations. In ceramics, glaze crazing results from a mismatch between the thermal expansion of the glaze and the ceramic body during firing and subsequent aging; additional stresses from handling, cleaning, or environmental changes can accentuate the cracking.

Craquelure is of practical importance in conservation, dating, and authentication. It can affect the stability of a work, trapping dirt and moisture, and may guide restoration decisions. Detection often uses magnification, raking light, or imaging techniques. While sometimes enhanced or simulated during restoration, authentic craquelure can provide valuable information about a piece’s history, materials, and condition.