Composition buttons are those made up, like a pudding, of a mixture of ingredients.
Composition buttons were mentioned in Australian print from 1865 until the late 1940s. The term was originally used for early attempts at cellulose based buttons, as seen in the following article, although later it just referred to any unspecified plastic mixture.
Note: Parkesine, the first nitro-cellulose based plastic, was patented by Alexander Parkes in 1856 and exhibited in 1862. It did not turn out to be a commercially viable product. Then celluloid was invented in 1865 by American John Wesely Wyatt. Later in 1891 Rayon was also developed from cellulose. These early plastics could indeed be quite flammable!
Composition buttons include, as mentioned yesterday, some apparently wooden buttons. These were produced in several eras; the second half of the 19th century, the 1920s and the 1950s, and consisted of wood pulp, fillers and pigments.
Some ‘hard rubber’ buttons are really composition, as are all gutta percha buttons, for gutta percha (from the sap of Malaysian trees) was never used on its own. Early phenol/bakelite buttons were also composition, as they included fillers such as wood fibre or even asbestos to make the material lighter.