Many of the materials used by bookbinders are commonly available like egg whites, wheat, and vinegar, while others are precious, like gold leaf. Materials are used for different leathers and different effects.
Gold leaf is gold that has been hammered into thin sheets by beating it. Layering gold leaf over a surface is called gilding. Bookbinders use gold leaf as an edge treatment, which protects pages from dust, bugs and humidity, as well as adding a rich, eye-catching decorative element to a book. It is also used in Tooling to enhance designs on the cover, back and spine. Gold leaf can be bought by the sheet, in booklets of 25 sheets and rolls, ranging in purity from 12k-24k.
Glaire is a mixture of egg whites and vinegar, strained and left to stand and is at its best aged for 1 week. In finishing is is used as a size to secure gold leaf when tooling. A single layer is sufficient unless tooling heavily. Today glaire can be made from albumen crystals or substituted with a ready-made liquid resin.
Bindings made of polished skins or imitation skins generally look better, and last longer if varnished. To apply, a small amount is poured on a pad or cloth and rubbed in a circular motion on all surface area. Bookbinders varnish is a rapid drying coating composed of shellac, sandarac, gum mastic, or a mixture of these resins.