Painter, etcher, and designer. Unusually versatile, he painted western scenery and romantically flavored foreign locales, spearheaded the American watercolor movement, and worked with Louis Comfort Tiffany on decorative projects. Also an early and knowledgeable enthusiast for Asian culture, he amassed a large collection of Japanese art and decorative objects. A native of Portland, Maine, Colman spent his formative years in New York and probably studied briefly as a young man with Asher B. Durand. At the outset of his career, he painted landscapes of the Northeast in the style of the Hudson River School. In 1860 he went abroad for two years, spending most of his time in Paris and Madrid, but also traveling through southern Spain to Morocco. During this time, he developed more fluent brushwork, as well as an increased sensitivity to effects of light. Probably inspired in part by the example of J. M. W. Turner's paintings, these characteristics also may reflect a growing interest in watercolor. After his return to New York, he served as the founding president of the American Society of Painters in Water-Colors (later the American Watercolor Society) from 1866 until 1870 and later remained active in its exhibition program. In 1870 he traveled for the first time to the West, reaching the Rocky Mountains. He may have returned the following summer before departing late in the year for four additional years in Europe and North Africa. Subsequently, his new enthusiasm for printmaking contributed to the etching revival then under way, and he numbered among the founders of the progressive Society of American Artists in 1877. In 1879 he joined with Tiffany and two others to form a collaborative interior design firm, Associated Artists. After the group disbanded four years later, Colman continued to work frequently with Tiffany on such sumptuous projects as the decoration of the 1890–91 Henry O. Havemeyer house in New York, a monument of the aesthetic movement. From the mid-1880s Colman reinvigorated his fascination with the West, traveling across the continent and visiting Canada and Mexico, as well. The subdued and personal western views of these years often achieve an intimate tone, perhaps reflecting an influence from his own collection of Barbizon work. After 1900 he increasingly turned his attention from painting to art theory, publishing his thoughts in two books, both written in collaboration with C. Arthur Coan. Nature's Harmonic Unity (1912) attempted to provide a mathematical basis for art. A sequel, Proportional Form (1920), appeared just before Colman's death in New York.