The temperature of the electrolyte affects the porosity of the anodic coating and can also affect the hardness and the thickness of the film. Under limiting conditions the coating will become softer and more powdery as the temperature rises since the effective temperature at the surface between the anodic coating and the electrolyte will be correspondingly higher, and this will also limit the maximum thickness attainable. lt is, therefore, necessary to pro­vide some means of keeping the temperature of the anodizing bath constant by suitable cooling.

Successful anodizing depends upon the ability to maintain uniform conditions throughout the anodizing cycle and to rapidly remove the produced heat. This means that the capacity of the refrigeration system must always exceed the maximum heat evolution of the anodizing bath plus eventual heat gain from the atmosphere.

For cooling the anodizing baths heat exchangers and circulation pumps suitable for acid solution are used.