Case 4

Cause of Defects

• Blistering may be caused by water seepage to the underneath of the paint film. Such blisters usually starts with a small patch and as water gets retained in the blisters, they start to grow bigger. When there is a built-up pressure due to water, the liquid is bottled up, the balloon formed and a surprising quantity is released when the blister is pierced.
• Moisture blister can also be formed by moisture migrating from the external to the internal. The water may be produced by leaks or simply by vapour generated by humidifier, dryers. If there is no vapour barrier , nothing stops moisture from moving under the paint film and cause blisters to peel.
• Another cause of moisture blisters is a high level of humidity in the internal environment. This is a likely cause if blistering is seen on walls outside the kitchen and bath where most water vapour is generated and is even more pronounced on the outside of the upper floor.
• Another cause for blistering to take places can be due to applying paint on warm surfaces (Figure 1a to e).