Method for continuously operating acid or alkaline zinc or zinc alloy baths

A process for the deposition of functional layers from acidic or alkaline zinc or zinc alloy baths containing organic additives selected from brighteners, surfactants and complexing agents;

• a soluble zinc salt and optionally further metal salts selected from Fe, Ni, Co, Sn salts, which process comprises the following steps:
• (i) providing a zinc or zinc alloy bath containing the aforementioned components,
• (ii) depositing a zinc or zinc alloy layer on the workpiece to be coated according to processes which are known as such,
• (iii) withdrawing a part of the zinc or zinc alloy bath and transferring the withdrawn part to a device for phase separation,
• (iv) adding an acid or base to the withdrawn acidic or alkaline part, wherein, when adding acid to the withdrawn acidic part, sufficient acid is added to reduce the pH of the withdrawn acidic part to a pH <1,
• (v) adjusting the temperature for acceleration of the phase separation,
• (vi) separating the organic phase and, if present, the solid phases,
• (vii) recycling the aqueous phase to the zinc or zinc alloy bath in such a way that the pH or hydroxide content of the zinc or zinc alloy bath remains within its operating range so that the bath can be operated without interruption, and
• (viii) replenishing spent components of the zinc or zinc alloy bath.