It is shown that in replacement of conventional raw materials by waste oxide catalysts, the wettability of enamels from charges with an elevated content of copper-zinc catalyst is improved. Replacement by aluminosilicate and especially iron-chromium catalysts worsens the wettability of the enamels. Replacement of an aluminosilicate catalyst by an iron-chromium catalyst also has a negative effect. © 1997 Plenum Publishing Corporation.