A box coating apparatus for coating of substrates comprises a vacuum chamber which contains an evaporation source. A substrate holder is disposed vis-à-vis to the evaporation source so that evaporated material can impinge on substrates held by the substrate holder. Besides the evaporation source and the substrate holder, at least one further functional component is provided, namely a Meissner trap and/or a high vacuum valve mechanism, to which a shield arrangement is assigned to prevent evaporated material from impinging on said component. This shield arrangement has a shutter portion which can be moved from a closed shielding position in which it covers a passageway through the shield arrangement and serves to shield said component, to an open pumping position in which it substantially clears the passageway to allow essentially free passage for gases and vapor, and vice versa.