Study of the effect of three anti-graffiti products on the physical properties of different substrates

Abstract To protect the surface of materials from the effects of graffiti paints, there are anti- graffiti products that prevent the penetration of these paints into the pore system of the substrates, making the substrates water- and oil-repellent, thus facilitating their removal. This paper presents a comparative study of three commercial anti- graffiti products (two sacrificial and one permanent) applied on three substrates, in order to evaluate the changes caused by these products on the physical properties of the substrates. Thus, the anti- graffiti products were applied on a Portuguese limestone and on painted and unpainted lime-based mortars. The experimental work was focused on various laboratory tests such as open porosity, capillary water absorption, water absorption under low pressure, water vapour permeability, drying behaviour and colour variations. The results have shown that these products introduced variations on the physical performance of the substrates, especially the water absorption, drying behaviour and water vapour permeability.