Indigo dye factory. 18th-century artwork of the processes used at an indigo dye factory. Indigo dye is extracted from plants such as Indigofera tinctoria. The plant's leaves are soaked to extract the chemical indican, which is then fermented to produce the dye (indigotin). This artwork is from a report forming part of a series describing arts and crafts for the French Royal Academy of Sciences ('Descriptions des arts et metiers'). This artwork is from the report 'L'Art de l'indigotier' (Paris, 1770) by Paul de Beauvais-Raseau, captain of a company of soldiers in Saint-Domingue (now Haiti) in the Caribbean.