Influence of paint systems on damp mortar substrates evaluated

Dampness is a common condition in old buildings Source: Uwe Malitz

Dampness is a common condition in old buildings and, accordingly, many paint systems specific for this type of building allow for application on walls with non-negligible moisture content. In spite of that, performance evaluation of these paints is normally carried out using dry substrates or even on free paint films. A new article in the "Journal of Coatings Technology and Research", Vol. 8, No. 4, presents research performed on 16 commercial paint systems. Each paint was applied and cured both on dry and on damp mortar substrates. The test specimens were subjected to water vapor permeability tests and evaporative drying tests. The conclusions: the way paint systems influence the drying of the substrate to which they were applied and where they were cured may vary significantly depending on the moisture content of that substrate; vapor permeability, measured with specimens applied and cured on dry substrate, may be an acceptable way of predicting a paint’s influence on drying, provided that the paints are applied and cured on dry substrate or that their characteristics are not significantly affected by the moisture content of that substrate.