On wide flat electrodes, the center does very little while the edges discharge the greater proportion of the ions. It's visibly obvious that there's a big difference while observing how electrodes wear away.
The back sides do virtually no ion discharging.
Corners and edges dissappear first, corners faster than edges, till finally you have a "U" that looks much like "V" with a rounded tip instead of a rectangle.
The newer electroplating electrodes are made in a "D" shape with the rounded side being the side not facing. This shortens the pathways from the back, eliminates the secondary backside edge that a block has and evens out the actual discharge area some.
Round shapes have no backsides, ineffective side facing flat centers, corners or edges, except for the end.... which will sharpen with the disproportionate discharge occurring there.
Distance counts.
The front of a round will go away a 'little' faster, [Which is why modern electrodes aren't 'round cylinders'] but swapping their postions between batches makes the former back the front and a piece of wire doesn't have the front/back distance differences that a 20 pound cylinder of copper has and the size/distance relationships aren't linear. ie, the smaller the diameter, the less the effect.[but also less surface area]
Bending the very tips away from each other a bit will prevent tip erosion to a great degree..or..don't put the ends in the water in the first place.
A round wire has ..almost.. twice the 'effective' discharge area than a flat rectangular electrode with the same surface area.
A square wire run with flats parallel will become a rounded wire...more "D" shaped, actually, with the rounded part facing as the leading edges do most of the work.
Ode [ex electroplater]
At 09:19 AM 11/12/2005 -0800, you wrote:
>>>>
Hi Faith,<<<<
Yes square would make a difference. The process is wet surface area dependent.
A square of one millimeter wire has more surface area than a one millimeter diameter wire.
The square would be 4 X width x wet length and the wire wouild be 3.1416 X diameter x wet length.
That difference would change the brew time for the same current density.
"Ole Bob"
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