My experience with die cast aluminum is that it does not anodize well because of the various alloying elements in A380. This powder is probably copper or other metal reacting with the sulfuric acid.

Al

Hi,

which anodising process do you use,

which temperature,

which current density?

RHABE

Aluminium casting alloys usually have some silicon in to help the metal flow but this detracts from the anodising process. If you can eventually get the anodising to work it is likely to have a very blotchy appearance.

In which case, was the anodizing facility informed of the type of aluminum being anodized?

Why didn't the Anodizing facility ask about the type of aluminum?

I think some liability rests on the Anodizing Facility.

Nign makes a good point as far as the Silicon content which runs from 7.5 to 9.5% in A380. I found that silicon in excess of 7% in A356 created problems for anodizing due to the cluster or islands formed by the silicon. Silicon itself is a very hard material and used in Duriron(14.5% silicon) for acid services and the anodizing is not effective in those areas causing spotting. Sub-surface pinhole porosity can also create anodizing problems. The anodizing house may have to increase wash/neutralizing times to insure any fluid which gets into those pores is removed before coloring. Sometimes experimentation is required if they are not familiar with castings.