Etching pretreatment in H2SO4+CuSO4 solution was applied to magnetron sputter-deposited Al–Si alloy films formed on a glass plate to improve uniformity of Zn deposition in the double zincate process. In the etching process, a small amount of Cu was deposited on the alloy surface at a very high density to accompanying Al dissolution. These deposits acted as nucleation seeds for Zn deposition, resulting in uniform, fine and thin Zn layers on Al alloys in a zincate process. This effect was more prominent on Al alloys containing 2.0 or 2.6 atom % of Si than on those containing 0 or 1.0 atom % of Si. Such a discrepancy was caused by increased Cu deposition on Al–Si alloys with relatively high Si concentration. ©2007 The Electrochemical Society