Gold Leaf
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
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.
Paste Water
Paste water is a starchy paste made of flour and water with a consistency of thin cream. It is sponged over porous leathers like sheep or calfskin and left to dry so that glaire will not sink into the skin.
Size
Size is made from gelatin dissolved in warm water. It is used when sheep or calf-skin bindings are to be polished and varnished. It is applied after the paste-wash has dried.
Vinegar
Vinegar is used as a cleaning agent and conditioner for non-porous leathers like morocco or seal. The skin is washed with this mixture prior to applying glaire.
Petroluem Jelly or Coconut Oil
A peroleum jelly (like Vaseline), or coconut oil, can be used as a temporary adhesive for gold leaf . A thin layer is is applied to a prepared leather surface with a soft cloth like cotton-wool.
Benzine
After gold tooling, and after removing excess gold with a gold rubber, a benzine-damped cloth is used to remove any grease or remaining fine particles.
Varnish
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.