Its purpose is to rapidly prepare the surface to be gilded. It is available in the three classic tints: red, yellow and black; it may be used as-is or diluted with water until the desired thickness is achieved. For an optimal preparation of the primer, it is always recommended to brush down a layer of base coat, then apply a layer of bolus with a soft brush. Once dry, smooth down with abrasive paper. Repeat the operation 2 or 3 times, until the surface is smooth and glossy. Apply one or two layers of adhesive primer on the primer prepared as above, then apply the gold leaf.