Most paint problems arise from plastered surfaces not being sound, dry and clean before the coating is applied. These three factors are part of Plascon’s key requirements for aesthetically appealing and long-lasting surfaces.
A sound surface is one prepared with plaster that’s been mixed in the right ratios using high-quality ingredients, which is then professionally applied and properly cured.
Cracks in plaster – even hairline cracks not clearly visible to the naked eye – compromise coating systems, as they expand and contract with the surface and can ultimately crack the paint. Cracks are often caused by plaster surfaces drying out too quickly before they can form cohesive strength – avoid this problem by wetting newly plastered surfaces to ensure the plaster remains hydrated. Plascon Professional Elastoshield, a highly elastic coating that can withstand repeated contraction and expansion over fine cracks, is ideal for use on plaster surfaces that are prone to cracking.
Just as plaster drying too fast can cause problems with coatings, so can plaster being too wet. Painting over damp plaster or water ingress through cracks result of water migrating through the cementitious substrate carrying high-pH lime particles to the surface. The evidence would be white, salty-like layers, called efflorescence and spotty discolouration of the paint, called alkaline burn.
This damp problem can be exacerbated by high humidity levels in the air, leading to surfactant leaching. Surfactants are compounds added to paint to promote stability and even spreading, and usually they either dry off as the paint cures or seal into the paint. However, when drying conditions are especially cold, steamy or damp, or when plastered surfaces aren’t allowed to dry completely before being painted over, the compounds leach to the paint’s surface in an uneven film that can look oily or sticky. So always ensure the plaster is completely dry before applying a primer, such as Plascon Professional Alkali Resistant Plaster Primer.
Poor, aesthetically unappealing plaster finishes require high-cost coating systems to be applied by skilled painters Quality coating systems such as the Plascon Professional Bridging Compound and Professional Marroca Coarse Texture help protect and improve the appearance of uneven plastered surfaces.
Regular maintenance assessments are important for all building projects to identify and address problems so that they can be resolved before major damage occurs. This not only helps the client to manage maintenance costs but will also extend the life of the coating system.