The technique involves grinding colored glass or enamel pigments to a talc-like powder, mixing it with water or oil (Patek Philippe usually uses lavender oil), and painting the resulting paste meticulously (sometimes using a brush as fine as a single hair) onto a prepared metal surface. Once dry, the paste is fired in a kiln at temperatures of around 850°C, so that the powdered glass or pigment melts to form a new, impregnable surface and fuses to the metal base.Dozens of firings may be needed as multiple layers are built up;