Anodizing welded sections

[sage]

I had my first occasion to anodize TIG welded aluminum. I used the proper Lincoln approved filler rod which off the top of my head was 5356. The 6061 of the part anodized perfectly, the weld metal itself anodized perfectly with the same final red colour as the 6061, but the point were the two (I assume) combined turns a bit black, like a shadow following a line beside the weld. If you can imagine a corner weld, the base metal is fine and the weld is fine but there is a shadow along both sides of the weld bead. I did not desmut the part before anodizing.

Has anyone had this experience? Any suggestions?

Sage

[archimedes]

greetings sage,

I have seen this problem occur in many instances with machine
shops having parts repaired through filler tig welding, re-machined
and then anodized. Didn't work out so well.
But then I have myself received anodized rims from Buchannan's
(maker of Sun rims in CA) had them stripped of the anodize and
personally looked straight at a machine made butt weld!
But I could not have believed this before I stripped the anodized
layer. I think Buchannan's use an anodizer who has figured
something out . . . . .
Secondly, there is a professional finisher's forum on the internet
www.finishing.com and these guys might have some answers or suggestions for you. This is the first place I found some of Fibergeek's discussions regarding the genesis of the LCD system while I was doing my own research. So it seems a pretty
knowledgeble resource. 2 areas of interest would be to write a letter of
inquiry and/or review the letter's archives. Those archives can be very
interesting and rewarding, if you have the time -- there's a lot 'em!

hope this helps,
archi

[sage]

Thanks I'll ceck out finishing.com

Sage