The different effect of two paint systems on moisture buffer capacity of traditional and modern plasters

• Published in: Journal of Building Engineering 2024-08, Vol.91, p.109701, Article 109701
• Main Authors: Ranesi, Alessandra, Veiga, Rosário, Rodrigues, Paula, Faria, Paulina
• Format: Article
• Language: English
• Subjects: Acrylic paint; Coating; Moisture buffer; Vinyl paint; Water vapor permeability
• ISSN: 2352-7102; 2352-7102
• DOI: 10.1016/j.jobe.2024.109701

Plasters can be finished with paint systems that can affect their moisture storage and transport properties. To confirm that, eight traditional and modern plastering mortars and pastes – based on cement, natural hydraulic lime, air lime, earth and gypsum - were coated with a vinyl paint (A) and an acrylic paint (B) and underwent the same hygroscopic characterization of the bare mortar samples. The effect of paint system A on water vapor adsorption and moisture buffering was small, in some cases positive. However, all the plasters painted with system A showed lower water vapor permeability than the bare plasters. The variation in the thickness of equivalent air layer was not the same for all the plastering mortars and pastes, suggesting that the different plastering substrates were still involved in the hygroscopic mechanism. The application of paint system B, instead, significantly reduced the hygroscopic behavior of the plasters, leveling their responses. The two paints, produced for different scopes and so with different kind and contents of constituents, have a diverse effect on those properties. Therefore, to optimize the passive contribution that plasters may have to indoor comfort, it is important to make a conscious choice when choosing paint finishing systems. •The effect of a vinyl (A) and an acrylic (B) water-based paint on hygroscopicity was evaluated.•The water vapor permeability of all the plasters decreased after vinyl paint A application.•A small effect of paint A on water vapor adsorption and on moisture buffering was observed.•With vinyl paint A the different plastering substrates were found to be still involved in the hygroscopic mechanism.•Paint B reduced the hygroscopic behavior of the mortars, leveling their responses.