[Mr. Pink]

hey, just wondering, if you have an entire surface of some aluminium thing anodized, dyed and sealed, if you sand off some of the ano-produced Al-Oxide in one area and re-anodize it, would it produce an unsealed Al-oxide coating on the sanded-down part while leaving the sealed surface undisturbed?

[Xeluc]

im going to give you the sohrt and long answer:
Short: no

Long:
Theoretically, this would work. the thing is, when you sand down an anodized part and put it back in acid.. you have the part being anodized, but the sulfuric acid is also eating away at the previously anodized part. Realize that if your part is colored do not attempt to reanodize as the coloring will be destroyed. I am not very familiar with anodizing (never done it but since reading this will try ) but basically what will be happening is your bare aluminum will be anodizing while the previously anodized part will be getting eaten away and replaced immediatly with new Al(OH)₃. It looks like it'd work ok as long as it wasnt dyed, but heat might be an issue. Make sure it doesn't get too hot. Thats about all the info I can give you.. Of course you said your part was dyed. So the best advice I can give you is to strip the entire anodizing off with Sulfuric acid.. then reanodize the whole thing and re-dye. Hope I helped