An early 70s edition of Design from Scandinavia reveals the material that architects Sidse Werner and Leif Alring used to create the light-transmitting but non-dazzling domed tops of their Formland lamp series for Fog & Morup (pictured below). "The metal parts of the fittings," it explains, "are lacquered in white, red, turquoise or yellow, and the shining calotte is made of butyrate, the only material that permits one to look at the filament of the bulb without being dazzled by it."

The Polymer Plastics Corporation tells us that butyrate is "a cellulose ester modified by using butyric and acetic acids, producing cellulose acetate butyrate, or CAB. Unlike other common synthetic plastics, the cellulosic plastics are not manufactured by polymerising a monomer. Instead, they are produced by the chemical modification of cellulose, a natural polymer. Cellulose itself is not a thermoplastic, since it will not melt. Yet by the viscose process, it is made into film (cellophane) and into fibre (rayon) that compete with the products of its thermoplastic derivatives.

"Cellulosics as a group are characterised by good strength, toughness and high surface gloss. In addition, they have good chemical resistance, good clarity, sparkle, and will take decoration readily. CAB is tougher than acetate and has lower moisture absorption. It resists weathering and has excellent transparency. Although it is adversely affected by alcohol, alkalis, paint removers and acetones, it is resistant to most household chemicals. Additionally, CAB is resistant to the harmful effects of ultraviolet radiation."