Piece of Italian design history that is part of the well-known process of testing conducted in 1960 by the Castiglioni brothers, of reinventing a material used in other contexts and scaling it according to the object in question. It was a patent of the Merano-based company Heisenkeil and acquired by Flos, for sprayed polymer plastic fibres that only subsequently solidify to form a strong, flexible membrane. The Castiglioni brothers saw this material used on American military vehicles to protect jeeps and tanks from the effects of bad weather and salt spray, and decided to use it for their lamps with a steel wire structure covered by sprayed resin.