Russian icons are painted with egg tempera on a wooden medium which is usually made of linden and is supported on its reverse by horizontal wooden bars. The obverse is generally dressed with linen on which the preparation for painting, a mixture of plaster or chalk with sturgeon or animal glue and linseed oil, is applied. The preliminary sketch is drawn according to the models or instructions of iconographic manuals; it is made with charcoal and is accentuated with ink. The finished painting is coated with a protective layer of “alifa”, a varnish consisting of progressively drying linseed oil and amber. Gold, mixed with egg white and occasionally combined with boll is used for gilding, while gold sheet is employed for gold striations, either plain, in which case it is applied according to the “inakop” technique, or dissolved in sour cherry-tree glue and mixed with egg white. Egg-yolk and “kvas” are the cohesive agents of pigments.