The Manufacturer and Builder 12, 1877
There are several processes for giving natural colors to photographs, but to do it satisfactorily one must be an able artist. One way is to simply color them with transparent water-colors, such as anilines; this is the easiest, but also the least artistic. Another way is to treat them like miniature water-colors; this is adapted for small photographs. Another way, best adapted for large life-size pictures, such as are thrown up by the solar camera, is to treat them with pastel; this, in able hands, gives a splendid effect. The most elaborate is what our correspondent mentions especially - photo all paintings; to produce these the prominent photographers in large cities employ a special artist who understands portrait-painting in oil colors. The picture is photographed on canvas, and this is only used by the artist as an outline for position, etc., during his treatment. What there is of the photograph becomes entirely invisible and covered up by the paint. There is no process nor is there any chemical for "changing a photograph to natural colors;" it is simply done by painting, and to do it well you must learn to paint.