After a print came off the press, usually in black ink, color could be added by hand. The artist often did the coloring himself or provided a guide print with instructions for a team of colorists. Because each image was individually hand-colored, variations could be observed from one edition to the next. Hand coloring was popular for natural history illustration because the wide range of watercolors allowed for the accurate representation of plants and animals. Even after color printing was technologically feasible, the highest quality illustrations continued to be hand done until the middle of the nineteenth century.