Swiss Aluminium Ltd.

Sandoz Gmbh

Schweizerische Aluminium Ag

Fritz Schneeberger

Walter Zweifel

Hans Bohler

Jean-Francois Paulet

Bruno Boetsch

Gunther Tscheulin

Hermann Weber

In acidic Sn(II)-containing electrolytes for coloring oxide layers on anodized aluminum or aluminum alloys, or for electroplating, the Sn(II)-ions are oxidized. By the addition of substances, so called stabilizers, to the electrolytes this oxidation can be more or less prevented i.e. Sn(II) can be more or less stabilized. Furthermore, the effectiveness of the stabilizer can be decisive for the quality of the deposit or the coloring of the oxide layer. It is known that the presence of substantial amounts of Sn(IV) along with Sn(II), as a result of inadequate stabilization of the Sn(II), impairs the quality of the surface treatment. An acidic, Sn(II)-containing electrolyte containing an addition of at least one soluble diphenylamine or substituted diphenylamine derivative stabilizes the Sn(II) and produces flawless coloring.

Improvements in processes for coloring anodized aluminum and/or aluminum

The solution for sealing anodic oxidized aluminum or aluminum alloys comprises basically an aqueous solution containing an addition of 0.1 to 2.5 g/l, made up of Agar-Agar and gelatine. the optimum pH value for the solution lies between 5.5 and 6.0. The sealing is carried out at a temperature between 90.degree. C. and the boiling point of the solution.

Sealing solution and process to prevent deposits forming during the

The present invention relates to an improvement of the method for electrolytic coloring of anodically produced oxide layers on aluminum and its alloys, by electrolytic treatment in a metal salt (Ni, Co, Cu) solution. It is characterized in that one establishes in the coloring electrolyte a content of 0.02 to 0.75 grams copper per liter. The method permit uniform and reproductible coloring to be undertaken in a simple manner.

Method of coloring of anodized aluminum and aluminum alloys by

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Schaffhausen, Switzerland

Fritz Schneeberger