the invention concerns an installation wherein is performed a crosslinking operation for a coating such as an ink or a varnish through ultraviolet radiation or electronic beam , in the presence of a gas mixture with controlled oxygen residual content . the installation comprises a chamber including one or more uv lamps or a source of accelerated electrons , required for performing the crosslinking operation , and is characterized in that it comprises an input device adjacent the chamber comprising at least the following three components , viewed successively by the product moving to be treated : a labyrinth system , means for injecting an inert gas forming a gas knife and a channel .