To ensure a performing demoulding, a release agent must resist the friction of concrete on the formwork. Emulsions are interesting alternatives that leads to a reduced consumption of oil on construction sites. The behaviours of two commercial emulsions are compared with two conventional demoulding oils. The adhesion energy calculated were favourable to the emulsions. The water evaporation kinetics leads to the measurements of film thickness. Tests with the tribometer have shown that the films produced from the emulsions generate a friction reduction of 30% and 40% at the concrete/formwork interface. Such performance can be explained by Wenzel's state of wettability, which facilitates the film fit into the formwork roughness.