Colloidal silver as innovative multifunctional pigment: The effect of Ag concentration on the durability and biocidal activity of wood paints

This study aims to assess the effect of two different colloidal silver amount on the durability and biocidal activity of a water-borne wood paint. The influence of this multifunctional pigment on the aesthetical features of the coatings was evaluated by colorimetric measurements and optical microscopy observations. The durability of the samples was investigated by means of different accelerated degradation tests, such as the exposure in a climatic chamber and to UV-B radiations. Scanning electron microscope observations, infrared spectroscopy analysis and colorimetric inspections were carried out to highlight the residual influence of silver in altering the protective behavior of the paint. Moreover, the Ag-containing samples exhibited excellent antibacterial activity against Staphylococcus aureus and Escherichia coli, while colloidal silver did not introduce effective fungicidal performances against Coniophora puteana and Trametes versicolor fungi. Ultimately, this work demonstrates how colloidal silver can be used as a functional pigment in wood paint, capable of modifying the appearance of the coating, improving its antibacterial performance, without negatively affecting its protective performance.