Constant Current Anodizing Rev 2

At a glance..

The method of constant current anodizing described here is a departure from the traditional open-loop voltage source method used for decades by amateurs.

The details..

'Constant Current Anodizing' introduces a new approach to amateur anodization of aluminum. The author proposes using a closed-loop current source instead of the traditional open-loop voltage method. This results in greater consistency and safety during the process.

The book delves into how this current source works by presetting it to a desired current that will maintain itself throughout the process. As the resistance increases with each layer formed, so does the applied voltage until peak anodic resistance (PAR) is reached. At this point, growth slows down as sulfuric acid dissolves some of it away.

For practical application purposes, any lab-type adjustable power supply can be used as long as it has constant-current operating mode capability. PAR detection can also be achieved when using a voltage source by monitoring both voltage and currents while adjusting accordingly.

Finally, Constant Current Anodizing' provides guidelines on several parameters based on years-long experience: maximum density for easy dyeing; time required to reach PAR; electrolyte temperature range; cathode material type/surface area ratio; electrolyte concentration/volume needed for avoiding shadow effects in thickness measurement.