Copper pipes can be painted, but they require special attention. Before painting them, the pipes must be free of oxidation and covered with an acid etch, two-component metal primer.
To remove the oxidation or discoloration on a copper surface, the pipes must be sanded until the copper has a nice shine. If this doesn't work, acid-based materials, such as vinegar or even stronger chemicals, must be applied until the copper is free from discoloration. The primer binds with the copper so that it does not pull away. Goggles, gloves and long sleeves are a must when applying this kind of primer.