Patent ID: 7767263

Claim:
A method of manufacturing a mould part ( 8 ) for forming an article, said method comprising: providing a master ( 1 ) of an aluminium alloy or a zinc alloy with a surface ( 7 ) corresponding to the surface of the article to be formed by the mould part, depositing a copper layer ( 3 ) on top of the master surface ( 7 ), plating a mould part layer ( 4 ) of nickel, a nickel alloy, cobalt or a cobalt alloy on top of the copper layer, dissolving the master ( 1 ) in a solution, selective etching the copper layer ( 3 ) from the mould part layer ( 4 ) in an alkaline etchant comprising free Cu(II) ions, a first complexing agent forming strong complexes with Cu(I) ions but not Ni ions or Co ions, a second complexing agent forming strong complexes with Cu(II) ions but not Ni ions or Co ions, and where oxygen is supplied to the etchant for oxidizing Cu(I) ions to Cu (II) ions.