Visual functions of mental imagery

Bright zinc plate is obtained from alkaline, cyanide-free zinc plating baths containing at least one linear polyamine obtained by condensing an aliphatic diamine with an aliphatic dihalide. Especially good results are obtained if the bath also contains at least one substituted pyridine compound in the form of a free base or as a quaternised derivative. A brightener composition containing both the linear polyamine and the pyridine compound can be added to alkaline, cyanide-free zinc plating baths.