These data were of necessity obtained over a relatively short test  period, and new anodes were used for each test.  If such a test were to be  conducted over a long period of time and under simulated production conditions,  where the anodes are alternately in active use and idle in the tank, film  buildup would occur on the inactive backsides of the flat anodes, reducing the  effective area and, it can be assumed, increasing the voltage difference between  the two types of anodes.
  Because the round anode has a 100 percent active  surface there is less chance of building up undesirable films which would result  in increased resistance.  Thus, higher currents can be used without undue  heating.  A round anode with a homogeneously burned-in hook would represent the  desirable type.
  The detailed test conditions are shown in Fig. 3; the  curves resulting when the voltages were plotted are shown in Fig. 4.
  It  will be noted approximately 6 percent more voltage was required to maintain the  chosen amperage with the flat anode than with the round, despite the fact that  the flat anode contained 7 percent more area and thus should have required a  lower potential.

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