Case 1

Introduction

Type of Building: Public

In this case, fine hairline cracking in a random pattern over a large area of wall on this painted wall is observed. This is often referred to crazing which is characterised by irregular cracks typically between 6 and 75mm across, and is also referred to as map or web cracking. The cracking of paint film has occurred due to the crazing of its substrate; plaster. Non-structural cracks such as crazing of the plaster coat may not cause any damage to the system.

These crazing cracks can develop at an early age and are apparent a day after placement or at least by the end of the first week. Often they are not readily visible until the surface has been wetted and it is beginning to dry out. Poor surface curing, too wet mix, bleed water when toweling and sometimes carbonation may be possible causes for the defect.

Crazing of paint cause either by the plaster behind the paint or by the paint itself may appear in the following forms:

There are similar cases where crazing of the paint is related to water seepage. For more information on paint crazing due to moisture, please refer to Paint Blistering.

Whether it is crazing or blistering, is not dealt with promptly, peeling and eventual flaking are most likely to follow.