The areas for water-gilding would initially be under-painted with layers of soft, pigmented clay called 'bole'. Not only did this provide a soft surface for the burnishing of the gold leaf, but the orange-red colour of the bole, gave a warmth to the semi-opaque gold leaf, which would otherwise have had a greenish tone if laid directly on the white surface.
Once dry, the layers of bole would be lightly burnished or polished with a cloth. Gold leaf would then be cut into small pieces, picked up with a piece of card and set down on some bole that had been wetted with water and a dilute size made from egg-white. The gold leaf was sucked down onto the wet surface to which it adhered.
The process was repeated until the area to be gilded was thus covered with pieces of gold leaf. The wrinkles were removed and a gleaming surface achieved by gently rubbing the gold leaf with a hard polished stone attached to a handle, a process known as burnishing.
