Cellulose acetate

Acronym and details:   CA

Group:   thermoplastic

Developed:   first prepared 1865, adapted to form viscose silk 1892, but only developed as a hard material for commercial use from 1918 (although to form cellophane from 1908); not common until late 1920s. Use fell off in1970s but interest currently reviving, as made from wood based cellulose, a renewable resource.

Trade names:   Celanese, Estron, Plastacele, Bexoid, Tenite, Clarifoil

Manufacturing process:   early examples compression moulded; from c.1928 injection moulded

Cost:   medium

Colour:   any, usually plain but occasionally marbled

Transparency:   transparent to opaque

Rigidity:   strong but slightly soft, may be flexible in thin sections

Feel:   hard

Smell:   vinegar (when degrading)

Other:   will accept surface colouring

Typical uses:   as liquid to stiffen and waterproof fabric wings and fuselage of early aircraft. In solid form in spectacle frames; type-writer keys; negatives and film; toys; fancy goods e.g. by Lalique; sculpture e.g. by Naum Gabo; hair brush handles, especially Addis Ltd; also as supports for archival material from 1940s

Degradation:   shrinks, crazes, becomes ‘sugary’ and cracks. Acidic droplets; white bloom on the surface; and distortion (warping), a result of plasticiser migration