Types - from Wikipedia
Astragal ? A semi-circular molding attached to one of a pair of especially fire doors to cover the air gap where the doors meet.
Baguette ? Thin, half-round molding, smaller than an astragal, sometimes carved, and enriched with foliages, pearls, ribbands, laurels, etc. When enriched with ornaments, it was also called chapelet.2
Bandelet ? Any little band or flat molding, which crowns a Doric architrave. It is also called a tenia (from Greek ?????? an article of clothing in the form of a ribbon.2
Baseboard, "base molding" or "skirting board" ? used to conceal the junction of an interior wall and floor, to protect the wall from impacts and to add decorative features. A "speed base" makes use of a base "cap molding" set on top of a plain 1" thick board, however there are hundreds of baseboard profiles.
Baton ? see Torus
Batten or board and batten ? a symmetrical molding that is placed across a joint where two parallel panels or boards meet
Bead molding ? narrow, half-round convex molding, when repeated forms reeding
Beading or bead ? molding in the form of a row of half spherical beads, larger than pearling
Other forms: Bead and leaf, bead and reel, bead and spindle
Beak ? Small fillet molding left on the edge of a larmier, which forms a canal, and makes a kind of pendant.2 See also: chin-beak
Bed molding ? a narrow molding used at the junction of a wall and ceiling. Bed moldings can be either sprung or plain.
At their simplest, moldings are a means of applying light- and dark-shaded stripes to a structural objects without having to change the material or apply pigments. The contrast of dark and light areas gives definition to the object.
Imagine the vertical surface of a wall lit by sunlight at an angle of about 45 degrees above the wall. Adding a small overhanging horizontal molding to the surface of the wall will introduce a dark horizontal shadow below the molding, which in consequence is called a fillet molding. 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.
Decorative moldings have been made of wood, stone and cement. Recently moldings made of Expanded Polystyrene (EPS) as a core with a cement-based protective coating have become popular. These moldings have environmental, health and safety concerns that were investigated by Doroudiani et al
Molding and coving - what is it?
Molding, or moulding (Commonwealth), also known as coving (UK, Australia), 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 made from plastic or reformed wood. In classical architecture and sculpture, the molding is often carved in marble or other stones.
A "sprung" molding has bevelled edges that allow mounting between two non-parallel planes (such as a wall and a ceiling), with an open space behind the molding. Other types of molding are referred to as "plain".