Causes High alkali or high salinity is a typical cause of corroded wood panels. As wood boards contain cement and asbestos, the surface can be high in alkali. Alkali urges an interactive effect with the paint film by deteriorating the latex-based adhesives and fading the primary colour pigment. These cause the fading and chalking of paint. Other causes may arise from high humidity of wood due to rainy season, ageing paint, low-quality paint or inappropriate use of paint.
Solution Remove corroded paint using a stiff brush and wash with clean water. Alternatively, do the power washing. Leave dry. Apply the primer on original substrate and refinish.