Superfici vetrate e limiti della conservazione nelle architetture del moderno

The glazed and transparent surfaces constitute a frontier of restoration. The policies of integral conservation concern the glass systems of the ancient historical heritage, defined by the "Guidelines" of the CNR and of the C.V.M.A. On the other hand, the consideration of the window-glass technological unit of modern heritage opens up different perspectives and presents different degrees of invasiveness, reversibility and compatibility. The paper highlights, on the basis of international studies - from Burra charter to the guidelines for protection - the role of knowledge, communication for valorization and guidance tools, for different levels of intervention. The choices on glazed surfaces are analyzed with reference to case studies of industrial and modern heritage, between the 19th and the 1950s of 20th. These processes are defined as: improvement maintenance; affixing added elements consistent with the frames; integration of movable shielding; glass replacement with high performance types; replacement of components and profiles and design reconstruction; replacement of the technological unit with different and multi- performance types, which are compatible with the recognized value of the architecture. The analyzed interventions - with reference to a sector literature and technical practice over thirty years - bring out the role of technological innovation and image construction, between permanence and compatible replacement.