Development of a water-based acrylic paint with resistance to efflorescence and test method to determine the appearance of stains

Abstract

Efflorescence are crystalline deposits of salts that appear on the surface of paints used to cover building walls. This pathology is not related to the quality of the paint, but to the quality of the construction buildings materials when moisture leaches the salts inside them. In this way, the aim of this work was to develop a water-based acrylic paint with higher resistance to efflorescence stains. Initially, it was necessary to develop a method to detect the formation of efflorescence in a short period of time. The method with the best results was to submit the ceramic specimen in aqueous solution of NaCl (5%). As the reference paint showed efflorescence stains, test paints were developed using two surfactants (polyether dimethylpolysiloxane and hydroxy thioether) at 0.1 and 0.6 mass % concentrations. Also, elastomeric, and acrylic styrene resins were added to the reference paint. The rationale for the use of surfactants was to reduce the surface tension of the paint on the surface of the masonry, making the paint flow better into the pores and, consequently, blocking the migration of salts to the surface. However, the contact angles of the developed paints on the masonry surface were greater than the reference paint, that was waterproof. If the solid surface were porous, perhaps the results would be different. Finally, it was possible to develop a paint resistant to stains caused by efflorescence, using elastomeric resin.