Bibliography & Glossary
Bole – a fine grained clay substance used during the gilding process.
Applied in liquid form over the gesso layer, the color of the bole (yellow, red, white, brown, black and blue)will affect the tone of the gold laid on top of it.
Burnishing – a technique in finishing water gilding. Using a tool called a burnisher (made most often with an agate stone) selected areas of the frame are polished to create highlights and contrast with the matte areas.
Butt joint – when two lengths of wood are joined together and secured by the use of plates.
Butterfly key – a shaped piece of wood inset on the back of a frame to secure the miter.
Composition (Compo) – a casting material made from whiting (calcium carbnate) , hide glue, resin and linseed oil. Pressed into carved boxwood molds, it was then removed and applied to the wood substrate.
Gesso – a liquid mixture of chalk (calcium carbonate), hide glue and water. Several coats are applied to the wood to prepare the frame for gilding.
Gilding – there are two techniques in applying gold leaf. In Water Gilding a mixture of alcohol, water and hide glue is applied to the bole layer. This adhesive will then hold the gold leaf laid on to it. Once dry the frame can be burnished.
Oil Gilding consists of an oil based size applied to the bole to which the gilding is applied. Oil gilding cannot be burnished thus keeps a matte surface.
Gold leaf – gold that has been pounded down into sheets or leaves nearly 1/250,000 of an inch thick. The variety of gold can differ from deep gold(23K) to lemon gold(18K),pale gold(16K) and white gold(12K) which are alloyed with small amounts of silver.
Lap joint – a corner joint where the end pieces of wood are partially
cut away to overlap smoothly.
Metal leaf – an alloy of zinc and copper used as a substitute for gold leaf. It is warmer in color, not as fine in texture, and darkens (oxidizes) with age.
Miter joint – where the wood is cut at a forty five degree angle and joined to a corresponding piece. The simplest and most common of joints, especially in American frames.
Miter joint with spline – similar to the miter joint with an additional spline or tapering key added to secure the joint. Commonly found in frames of European origin.
Mortise and tenon – a joinery where one piece of wood (the mortise) has a notch, hole or space cut into it to receive a projecting piece of wood (the tenon).
Parcel gilt – gold leaf applied to selected parts of walnut and mahogany frames.
Patina – the natural or artificial discoloring of a surface.
Silver leaf – similar to gold leaf but it requires sealing with a finishing lacquer to prevent tarnishing.
Size – an adhesive used in gilding. It is often made from animal hide glue.
Replica – when a period frame is to be duplicated, the craftsman works directly with the original frame. Molds are taken directly from the original if ornament is to be cast and the frame is constantly referred to for its design and gilding attributes. This attention to detail allows for a faithful and sensitive facsimile.
Reproduction – when a frame is copied from sources other than an original period frame. They are generally of lesser quality than a replica in terms of crispness of surface detail, subtlety of gilded surfaces and overall sensitivity to patina.