Fig. 39. Bronze bull showing warty patina.
Fig. 40. The same after reduction by Finkener’s method[147].
There is no doubt that these bright-blue efflorescences are the result of an incomplete reduction, which in many cases can scarcely be remedied, for it is often impossible thoroughly to wash objects of great thickness. Thin bronzes, bronze plate, and copper plate remain free from efflorescences. Moreover, many bronzes, especially Egyptian ones, have a hard, non-metallic core, which in the casting has been partly fused or at least hard-burnt, and resists the effects of the washing.
Fig. 41. Bronze axe-blade before treatment by Finkener’s method (Aeg. 13203).