work area vs. cathode area

[elton10]

Is there some ideal ratio or rule-of-tumb ratio between the work area and cathode area for anodizing? Or is just that the cathode area should be larger than the work?

[Fibergeek]

If you are using the anode/cathode ratio to provide some current limiting (not recommended) then it would matter.
The simple rule for this in LCD anodizing is to have the cathode area larger than the anode area.
If you are using CC mode, any differences in the electrolyte conductivity caused by this ratio are automatically compensated for. This is one of the many advantages a current source has over a voltage source for anodizing or electroplating.

[elton10]

Fibre

Thanks. Actually Im NOT using a CC supply but I plan on mimicking CC by keeping a constant check and adjusting voltage.
We've got one of Caswell's 25A plating rectifiers but will likely get the 20A CC as soon as they get them in.

[Fibergeek]

OK. That should work.

[elton10]

Great and thanks again for the info