From the earliest days of the daguerreotype color has been applied to monochrome images by hand, pastels and transparent oil paints being the most common media. Applied with brushes and cotton swabs the results were rarely naturalistic when compared with modern color processes but that is part of their charm. Beginning with the first establishments, portrait studios offered hand colored prints until the advent of practical color processes in the 1960s. Also during this era, hand coloring black and white landscape photos was a popular hobby with kits being offered being offered specifically for this purpose. The Walter Nutting Studio developed assembly line techniques to produce large quantities of hand colored photographs for sale. Some portrait studios used more sophiticated airbrush techniques to color photos resulting in greater realism than could be achived with brushes alone.