Gold leaf is extremely thin and very hard to handle. To apply the gold leaf, you first put a thin layer of the egg white mixture on the panel, then pick up the piece of gold leaf and put it over the coated panel area. Next you take your brush and gently smooth the gold. This is very tricky and takes a while accomplish. The gold leaf is made out of gold or metal that is pounded into very thin sheets.
Some artists stamp different shapes in to the leaf.
Next, the assistants ground up different substances to create different pigments. The pigments are made from different minerals and clays, then mixed with egg yolks to thicken the paint and give it an opaque and sparkly touch. Very stiff brushes are used to paint with the pigment, which allows the artist to paint in great detail.