Causes : Crazing or sometime call hair line crack or map crack was cause by many factors such as;

• cement content in plastering mortar is too high
•  the finishing process (apply brushed water and final hawking) was done too earlier or lately
• the brick absorb some water from masonry mortar due to erection wall is too dry before plastering
• working apply in hot air, strong sun, strong wind which is low relative humidity and cause plastering mortar loss moisture rapidly