There has always been a demand for a satisfactory method of coloring copper after installation; particularly, copper roofing of various types. The patina developed by the alternate immersion process while sufficiently adherent for ordinary handling will, like natural patina, flake off on severe bending. This is, of course, objectionable on roofing where bending is necessary for forming seams. The patina is also destroyed by heating. A successful technique has been developed whereby copper roofs may be given a natural patina by a simple spray treatment. This process is described in this article.