A 100% He plasma leads to a better result than a helium–oxygen plasma. In fact, the latter kind of plasma was less homogeneous and more difficult to control; the eventual unevenness of the treatment while operating with the mixture He/O2 may represent a cause of the less effective plasma pre-treatment. Introducing oxygen in the mixture, from a chemical point of view, implies the increase of the oxidizing potential of the plasma itself and generates more oxygencontained radicals on the fabric surface, which probably do not promote any positive effect during the following polymerization step