Molding (decorative)

Molding (spelled moulding and alternatively called coving in British and Australian English), is a strip of material with various profiles used to cover transitions between surfaces or for decoration. It is traditionally made from solid milled wood or plaster, but may be of plastic or reformed wood. In classical architecture and sculpture, the molding is often carved in marble or other stones. In historic architecture, and some expensive modern buildings, it may be formed in place with plaster.

A "plain" molding has right-angled upper and lower edges. A "sprung" molding has upper and lower edges that bevel towards its rear, allowing mounting between two non-parallel planes (such as a wall and a ceiling), with an open space behind. Moldings may be decorated with paterae as long, uninterrupted elements may be boring for eyes.

Decorative moldings have been made of wood, stone and cement. Recently^[when?] moldings have been made of extruded polyvinyl chloride (PVC) and expanded polystyrene (EPS) as a core with a cement-based protective coating. Synthetic moldings are a cost-effective alternative that rival the aesthetic and function of traditional profiles.^{[citation needed]}

Common moldings include:

At their simplest, moldings hide and help weather seal natural joints produced in the framing process of building a structure. As decorative elements, they are a means of applying light- and dark-shaded stripes to a structural object without having to change the material or apply pigments. Depending on their function they may be primarily a means of hiding or weather-sealing a joint, purely decorative, or some combination of the three.

As decorative elements the contrast of dark and light areas gives definition to the object. If a vertical wall is lit at an angle of about 45 degrees above the wall (for example, by the sun) then adding a small overhanging horizontal molding, called a fillet molding, will introduce a dark horizontal shadow below it. Adding a vertical fillet to a horizontal surface will create a light vertical shadow. Graded shadows are possible by using moldings in different shapes: the concave cavetto molding produces a horizontal shadow that is darker at the top and lighter at the bottom; an ovolo (convex) molding makes a shadow that is lighter at the top and darker at the bottom. Other varieties of concave molding are the scotia and congé and other convex moldings the echinus, the torus and the astragal.

Placing an ovolo directly above a cavetto forms a smooth s-shaped curve with vertical ends that is called an ogee or cyma reversa molding. Its shadow appears as a band light at the top and bottom but dark in the interior. Similarly, a cavetto above an ovolo forms an s with horizontal ends, called a cyma or cyma recta. Its shadow shows two dark bands with a light interior.

Together the basic elements and their variants form a decorative vocabulary that can be assembled and rearranged in endless combinations. This vocabulary is at the core of both classical architecture and Gothic architecture.