A-Z of eyewear: ABC

First used to make spectacles in the late 1940s because of brittleness associated with previously-used plastics, acetate in cellulose form has gone on to become synonymous with eyewear because of the colour palettes that can be achieved and the smooth, luxury feeling when acetate has a high polished finish.

Cellulose acetate is not plastic in the traditional sense, as its main ingredient is cellulose powder, which is an extract of cotton. Cotton flakes are pushed and squeezed through a large press to form a transparent paste that is used as a base for the large sheets further along in the production process. Parts of the paste sections are cut off and put through heated rollers until it reaches the desired thickness. Coloured powders are carefully added and mixed with acetone and spread over the raw transparent acetate. The crudely coloured paste is then pressed again, until the colour is uniform. Granules of coloured acetate are mixed and once again subjected to another rolling process. Here a completely new piece of acetate is created, with different colours and textures. The material is placed in a press for around a day and the block is carefully sliced into large sheets, which go on to be cut into smaller pieces when they arrive at their frame production stage. Before this can happen, the acetate needs to cure, getting rid of any excess solvents. The acetate created in this fashion is described as extrusion acetate. Laminated acetate is made in a similar fashion as extrusion, but the sheets are placed on top of one another at the pressing stage and slowly bonded together.