Harry Bertoia (1915-1978) moved to Pennsylvania from California to work for Knoll in 1950. Knoll is the manufacturer and copyright holder of all Bertoia chairs. Chairs, based on steel grid wire forms, were designed by Harry Bertoia between 1950 and 1951 and further developed for production by Harry and the development team consisting of Richard Schultz, Don Pettit and Bob Savage in 1951 – 1952. They were first introduced in December 1952, and have enjoyed steady continuous production since 1953. To state the obvious, nearly all products that have been in production for over 63 years undergo evolutionary changes over time. Most are a response to field failures, structural improvement or cost reduction. Others are a response to external forces.
For the sake of discussion, one can consider all Knoll Bertoia chairs as being either early style (1986 and earlier) or late style (1986 and later). Prior to 1986, all Bertoia chairs were manufactured in East Greenville, Pennsylvania, or overseas by Knoll subsidiaries or under license. At various times, Bertoia chairs were manufactured in Argentina, Belgium, Finland, France, Germany, Italy, Japan, Sweden and Switzerland. All chairs of pre-’86 manufacture are very similar and are often only distinguishable by the wire diameters used (close metric diameter equivalent to US standard wire gauges.) See Photo 1 with yellow tags. It must be noted that, since foreign-made Bertoia chairs were never imported to the US, that it is very unlikely to encounter them here in the US.
All chairs made before 1986 are characterized by lightness and transparency. Harry liked to think of his chairs as being “mainly made of air.” That changed when the manufacture of the entire Bertoia line was shifted to Italy. At that time, the collection was retooled and major changes were made. Most obvious was the significant increase in wire diameter used throughout which changed the character of the chairs from transparency to form. See Photo 2.