Process for the surface treatment of a metering valve said metering valve comprising a valve body and a gate that slides in said valve body said process comprising a first step of forming by chemical grafting a thin silicone film on at least one support surface of said valve body and/or of said gate and a second step of applying free silicone to said grafted thin silicone film so that said treated support surface simultaneously comprises grafted silicone and free silicone the siloxane chains of the grafted silicone and of the free silicone combining chemically with one another in order to strengthen the holding of the free silicone on said grafted thin silicone film.
