became commonly known as Van Dyck brown. 19th and 20th century Brown was generally hated by the French impressionists, who preferred bright, pure colors. The exception among French 19th-century artists was Paul Gauguin, who created luminous brown portraits of the people and landscapes of French Polynesia. In the late 20th century, brown became a common symbol in western culture for simple, inexpensive, natural and healthy. Bag lunches were carried in plain brown paper bags; packages were wrapped in plain brown paper. Brown bread and brown sugar were viewed as more natural and healthy than white bread and white sugar. Brown in science and nature Optics Brown is a dark orange color, made by combining red, yellow and black. It can be thought of as dark orange, but it can also be made in other ways. In the RGB color model, which uses red, green and blue light in various combinations to make all the colors on computer and television screens, it is made by mixing red and green light. In terms of the visible spectrum, "brown" refers to long wavelength hues, yellow, orange, or red, in combination with low luminance or saturation. Since brown may cover a wide range of the visible spectrum, composite adjectives are used such as red brown, yellowish brown, dark brown or light brown. As a color of low intensity, brown is a tertiary color: a mix of the three subtractive primary colors is brown if the cyan content is low. Brown exists as a color perception only in the presence of a brighter color contrast. Yellow, orange, red, or rose objects are still perceived as such if the general illumination level is low, despite reflecting the same amount of red or orange light as a brown object would in normal lighting conditions. Brown pigments, dyes and inks Raw umber and burnt umber are two of the oldest pigments used by humans. Umber is a brown clay, containing a large amount of iron oxide and between five and twenty percent manganese oxide, which give the color. Its shade varies from a greenish brown to a dark brown. It takes its name from the Italian region of Umbria, where it was formerly mined. The principal source today is the island of Cyprus. Burnt umber is the same pigment which has been roasted (calcined), which turns the pigment darker and more reddish. Raw sienna and burnt sienna are