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.

Abstract: An aqueous acid nickel electroplating bath containing as a brightener-leveling agent the reaction product of an acetylenic diester of a halogenated saturated aliphatic acid with a heterocyclic compound containing a tertiary nitrogen atom. The brightener may have the general formula ##EQU1## wherein R.sub.1 and R.sub.2 are hydrogen, halogen or a hydroxy, carboxy, carboxyester, sulphoxy, alkyl, amino or amido group;R.sub.3 is a hydrogen or an alkyl group;R.sub.4 and R.sub.5 are hydrogen or an alkyl group;X is halogen andN is an integer from 0 to 2.