Politipo 72 is part of the homonymous cycle that Alberto Biasi begins in 1965 and which he will continue to develop throughout his artistic career. Polytypes are PVC lamellar structures, in which Biasi experiments with the infinite possibilities of formal modulation of the optical-dynamic object, to suggest the impression of movement. The artist plays on the different perceptions on the part of the observer, obtained thanks to the densification or rarefaction of the points and lines of the structure. Moving in space, the observer can in fact perceive dynamic or static images, based on the choice of moving or observing the work from a fixed position. Biasi articulates his art according to certain research canons: the spectator's interaction with the work becomes a fundamental and movement - in its passive sense of virtual motion - leads the artist to experiment research on visual perception and individual reaction. to the light stimulus. In the nineties, in fact, the Polytypes were enriched with further pictorial elements, in the form of insertions of color, traces, shadows, allusions that support the articulated structure of the layered surfaces. By deepening the research on the luminous impact of natural light, Biasi develops new solutions with hypnotic effects, created through twisting, overlapping of tops, intertwining of foils and strips. The game between spectator-actor and work becomes more and more articulated and free, confirming the absolute variability of perception in the spectator.