Crazing is a close pattern of narrow shallow interconnected cracks usually forming closed polygons. It can be apparent within a few days of casting but can occur at any time under appropriate climatic conditions. e.g. a period of low humidity leading to drying conditions.

Crazing may occur early in the life of the member but may not be noticed until the cracks are accentuated by dirt deposition.

Crazing can occur both on exposed surfaces and on surfaces in contact with formwork. It occurs either where there is a change in properties close to the surface or where there is a high moisture content gradient. The type of formwork is also important; steel and plastic formwork faces appear to increase the incidence of crazing.

The occurrence of crazing can be significantly reduced by adequate curing.