[mejia198021]

Hi,

I am currently working on a high school project on applying hard anodization to alloy aluminum tubes in oxalic acid.  As far as I know oxalic acid can sustain the high voltages compared to sulfuric acid that resists between (70-80) V.  Since hard anodization requires 100 V plus, the problem I am encountering is that my alloy Al tube is getting burned and after 1.5 hours of anodizing about 1-2 cm is burned off. 

Can someone suggest a solution or lead me in the right direction.  I would greatly appreciate anyone's suggested knowledge to this problem.  Thank you

[leoh]

I have a lot of experience with hard anodizing, although not much with oxalic acid anodizing.  The major cause of burning is inadequate solution movement.  Burning is localized overheating and to remove the heat you need a lot of solution movement.  Usually an air bubbler is sufficient but a mechanical stirrer is better.  The more solution movement around he part the better.  Keeping the solution cool is ls important, what is the temperature?  Also why are you using oxalic acid?