Abstract: A process for obtaining a range of colors of the visible spectrum includes a first phase to form an anodic film, a second phase to modify a barrier film and a third phase to deposit metallic particles on the barrier film. During the formation of the anodic film, a thickness in excess of 0.3 .mu.m is obtained. The electrolytic modification of the barrier film is carried out in a low dissolving power electrolyte, applying a predetermined low voltage and a predetermined low current density. The third phase is carried out by an electrolytic deposition of metallic particles in order to increase internal reflections under the deposit. The average voltage applied in the electrolytic modification of the barrier film is below 5 volts of a complex alternating current, and the average density of the current applied is less than 200 mA/dm.sup.2 of the complex alternating current.

Abstract: This invention relates to a process and composition for sealing anodically oxidized aluminum surfaces, the composition having an effective amount of a source of alkali metal ions especially lithium ions. The process of the invention involves contacting an anodically oxidized aluminum surface with the aqueous sealing solution of the invention.

Abstract: This invention relates to a process and composition for sealing anodically oxidized aluminum surfaces, the composition having an effective amount of a source of alkali metal ions especially lithium ions. The process of the invention involves contacting an anodically oxidized aluminum surface with the aqueous sealing solution of the invention.

Abstract: A two-step process and apparatus for the electrolytic coloring of anodized aluminum using an electrode and the anodized aluminum immersed in an electrolyte. First the aluminum is anodized to form an oxidized film on its surface and then a coloring step is performed. In the coloring step a modified sinusoidal voltage waveform is applied to the anodized aluminum and the electrode to color the oxidized film. Suitably gated thyristors in the secondary of a power supply may be used to provide the desired voltage waveform. The voltage waveform is generated with a leading edge rise time in the negative portion substantially longer than in the positive portion. The average negative voltage is greater than the average positive voltage to provide good throwing power, coloring speed, color uniformity and electrode dissolution, with tha capability to subtract color. Excellent throwing power with fair coloring speed is obtained if the average negative voltage substantially equals the average positive voltage.