Abstract: A pressure-sensitive adhesive based on a dimethylpolysiloxane gum for adhering porous and semi-porous substrates. The adhesive has thixotropic properties which permits the viscosity of the adhesive to breakdown when pressure from one substrate is exerted on another substrate which is in a horizontal position in order to allow a temporary adhesion. The adhesive is transparent, has a consistency of a gel, and a viscosity range that controls the flow of the adhesive and provides a bond that can be broken by physical separation of the two substrates.