PURPOSE: To produce a material to which patina is firmly attached.
CONSTITUTION: A copper layer is electrodeposited on a substrate at a current density above a limiting current density to roughen the surface, and a copper layer is integrally electrodeposited on the copper layer at a current density below the limiting current density to prevent the separation of powder from the copper layer. Metallic Ni or an Ni compd. is finely dispersed on the highly roughened copper electrodeposited layer from which powder is not separated, and patina is formed thereon. The contact area between the patina and copper electrodeposited layer is increased, the layer is anchored by the fine metallic Ni or Ni compd. and firmly attached to the substrate, and a beautiful appearance is maintained for a long period when the material is used as a roof board, etc.
TANI TOSHIO
IGARASHI MINORU
