What is a good rule to follow when it comes to matching current to anode size per square inch? Stong stirring will be applied.
With strong stirring (enough to cause non-laminar flow around the anode), you can push the current pretty high. Without stirring, the 6ma per square inch is probably as high as you can go. If you see brown smoke falling from the anode, your current is too high.
There is a layer surrounding the electrodes called the Nernst Diffusion Layer. The goal is to keep the concentration of silver ions within the diffusion layer below the solubility limit of the newly created silver oxides. When that is exceeded, the silver oxides precipitate and fall to the bottom of the flask.
Vigorous stirring keeps the silver ions swept away into the bulk fluid preventing the precipitation.
Since the solubility of silver oxides varies with temperature, temperature also affects maximum current per unit of anode surface area.
Diffusion Layer