Even if sometimes the final result may appear similar, water-repellent agents and sinking agents belong to two different families of products that operate through different chemical and physical mechanisms.

Water-repellent agents, currently available primarily in formulations based on organic solvents, act on the layer of material discharged on the substrate after their application (such as engobe, glaze suspension, ink, etc.), creating a repellent or isolating effect with the underlying material. This results in a lack of matter where the reserving agent has been discharged.

In other words, the water-repellent agent prevents the glaze from evenly settling, thereby preventing the formation of a perfectly flat surface. Reserving agents, that has been discharged before the subsequent watery applications, displace the glaze inhibiting its adhesion. The final result is the formation of a depression or dip.

The action of the water-repellent agent is immediate and can already be observed when the raw ceramic tile is on the conveyors of the glazing line. This action is based on various physical principles, among which the difference in surface energy between the area treated with the reserving agent and the rest of the surface plays a significant role.