Case 3
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- Causes of Defects
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Cause of Defects
This is the result of moisture content in the cement coming to the surface and attacking the dried paint film causing it to turn into small patches to a soap-like substance (Figure 1a to d).
When water is also present, it will produce soluble salts, which when in the presence of lime results in caustic soda solution.
When this caustic solution comes to the surface and makes contact with the fatty oil content of the paint the result is soap.
Often in the process, a change of colour occurs and saponification thus results.
It will result in the breaking down of the paint film thus encouraging moisture penetration. that will further destroy the paint film continuity.