A better way than an average conductive coating is metallization. The resistance of the metal on the plastic surface is lower, hence the shielding performance better. Coatings with metal particles always need a binder. Not all the particles will contact their neighbour for there can be binder between. Therefore a metal layer is mostly better.
During the common high-vacuum coating process by evaporation, first the metal melts and then creates a "cloud" of Aluminium vapour which will condense on a polymeric surface and create a thin metallic layer.
At the ideal vacuum condition(10 -4torr), metallic molecules gravitate towards the polymeric surfaces which have to be coated without encountering air or gas particles resistance. Before the high-vacuum coating process the polymeric surfaces have to be levelled and insulated by a primer coat(varnish), in order to allow the metallic layer to bed in correctly and promote the adhesion of the following transparent protection layer (f.e.: varnish).
The primer coat treatment undertakes three fundamental functions, which guarantee higher quality results:
aesthetic functions
insulating function
functional interface at layer adhesion points
Aluminium and metallic layers have both aesthetic and functional features, 80% of high-vacuum metallization processes give used for aesthetic purposes, but also functional application have been rapidly increasing, because of a change in galvanic processes, which are currently very expensive and above all are extremely dangerous for the environment. Recently multiple-layer cycles have been developed (high-vacuum metallization and subsequent formation of multiple-layer metals) in different fields, such as electronics, reflection, electromagnetic insulation, with first-class result from both an aesthetic and functional point of view.
Used for aesthetic purposes, transparent trimming is today undertaken by means of UV products due to their brilliant and vitreous characteristics which is reflected from the metallic or aluminium layer.
Varnish protection layer treatment protects aluminium and metallic layer from oxides and mechanical wear(or from chemical degradation, deriving from perfumes, essence, sweat) and represents the final coating phase, which is a highly cohesive multiple layer package.
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A better way than an average conductive coating is metallization. The resistance of the metal on the plastic surface is lower, hence the shielding performance better. Coatings with metal particles always need a binder. Not all the particles will contact their neighbour for there can be binder between. Therefore a metal layer is mostly better. 
At the ideal vacuum condition(10 -4torr), metallic molecules gravitate towards the polymeric surfaces which have to be coated without encountering air or gas particles resistance. Before the high-vacuum coating process the polymeric surfaces have to be levelled and insulated by a primer coat(varnish), in order to allow the metallic layer to bed in correctly and promote the adhesion of the following transparent protection layer (f.e.: varnish). 
