Bois Durci is a plastic moulding material based on cellulose. It was patented, in Paris in 1855, by Lepage. It is made from finely ground wood 'flour' mixed with a binder, either egg or blood albumen or gelatine. The wood is probably either ebony or rose wood, giving a black or brown result. The mixture is dried and ground to a fine powder. The powder is placed in a steel mould and compressed in a powerful hydraulic press whilst being heated by steam. The final product has a highly polished finish imparted by the surface of the steel mould.

It is not known when the production of Bois Durci objects, in Paris, was discontinued. However, it is known that another factory was established in 1883 in Sezanne by members of the Hunebelle family. This factory used the same material to produce very similar items. Although stylistically similar, it is almost certain that none of the moulds from Paris were used in Sezanne. The Sezanne factory continued in production, manufacturing both 'Belle Epoque' and 'Art Nouveau' items until the factory was destroyed by fire in 1926.

There are many different products made with this material.