Acetate
A plant-based plastic, cut from blocks, used for most coloured and patterned glasses frames.
Also: cellulose acetate, zyl
Cellulose acetate is made from wood pulp or cotton fibres. For frames it is made into blocks or sheets, often with layered colours or tortoiseshell patterns, then cut, shaped, polished and fitted with metal cores in the arms so they can be adjusted with heat. It replaced flammable celluloid and real tortoiseshell in the twentieth century. Italian makers in the Cadore and Japanese makers in Sabae are known for acetate work.