An apparatus and method for subjecting a material, such as an aluminum web, to an electrolytic roughening treatment. The apparatus includes a tank for storing an electrolytic solution, and for conveying the web through the solution. As the web is conveyed through the solution, it passes first and second electrodes, which are coupled to a power source circuit. The power source circuit generates an alternating current and applies the same to the electrodes. The circuit also includes a rectifying coil having an inductance (L.sub.1), which is at least ten times greater than the inductance (L.sub.2) of the load.