Hand-colouring (or hand-coloring) refers to any method of manually adding colour to a monochrome photograph, generally either to heighten the realism of the image or for artistic purposes. Hand-colouring is also known as hand painting or overpainting. Typically, watercolours, oils, crayons or pastels, and other paints or dyes are applied to the image surface using brushes, fingers, cotton swabs or airbrushes. Hand-coloured photographs were most popular in the mid- to late-19th century before the invention of colour photography and some firms specialized in producing hand-coloured photographs. History Pre-1900 Monochrome (black and white) photography was first exemplified by the daguerreotype in 1839 and later improved by other methods including: calotype, ambrotype, tintype, albumen print, and gelatin silver print. The majority of photography remained monochrome until the mid-20th century, although experiments were producing colour photography as early as 1855 and some photographic processes produced images with an inherent overall colour like the blue of cyanotypes. In an attempt to create more realistic images, photographers and artists would hand-colour monochrome photographs. The first hand-coloured daguerreotypes are attributed to Swiss painter and printmaker Johann Baptist Isenring, who used a mixture of gum arabic and pigments to colour daguerreotypes soon after their invention in 1839. Coloured powder was fixed on the delicate surface of the daguerreotype by the application of heat. Variations of this technique were patented in England by Richard Beard in 1842 and in France by Étienne Lecchi in 1842 and Léotard de Leuze in 1845. Later, hand-colouring was used with successive photographic innovations, from albumen and gelatin silver prints to lantern slides and transparency photography. Parallel efforts to produce coloured photographic images affected the popularity of hand-colouring. In 1842 Daniel Davis Jr. patented a method for colouring daguerreotypes through electroplating, and his work was refined by Warren Thompson the following year. The results of the work of Davis and Thompson were only partially successful in creating colour photographs and the electroplating method was soon abandoned. In 1850 Levi L. Hill announced his invention of a process of daguerreotyping in natural colours in his Treatise on Daguerreotype. Sales of conventional uncoloured and hand-coloured daguerreotypes fell in anticipation of this new technology. Hill delayed publication of the details of his process for several years, however, and his claims soon came to be considered fraudulent. When he finally did publish his treatise in 1856, the process – whether bona fide or not – was certainly