An easel is an upright support used for displaying and/or fixing something resting upon it, at an angle of about 20° to the vertical. In particular, easels are traditionally used by painters to support a painting while they work on it, normally standing up, and are also sometimes used to display finished paintings. Artists' easels are still typically made of wood, in functional designs that have changed little for centuries, or even millennia, though new materials and designs are available. Easels are typically made from wood, aluminum or steel. Easel painting is a term in art history for the type of midsize painting that would have been painted on an easel, as opposed to a fresco wall painting, a large altarpiece or other piece that would have been painted resting on the floor, a small cabinet painting, or a miniature created sitting at a desk, though perhaps also on an angled support. It does not refer to the way the painting is meant to be displayed; most easel paintings are intended for display framed and hanging on a wall. In a photographic darkroom, an easel is used to keep the photographic paper in a flat or upright (horizontal, big-size enlarging) position to the enlarger. The word easel is an old Germanic synonym for donkey (compare similar semantics). In various other languages, its equivalent is the only word for both the animal and the apparatus, such as esel and earlier ezel (the easel generally in full schildersezel, "painter's donkey"), themselves cognates of the asinus (ass). Easels have been in use since the time of the ancient Egyptians. In the 1st century, Pliny the Elder made reference to a "large panel" placed upon an easel. There are three common designs for easels: A Frame designs are based on three legs. Variations include: crossbars to make the easel more stable; and an independent mechanism to allow for the vertical adjustment of the working plane without sacrificing the stability of the legs of the easel. H-Frame designs are based on right angles.