Hello,

Recently we recived a costumer complaint regarding contamination in an aluminum part that is anodized (we bought this part), this contamination was detected in an inspection under black light (UV).
We are having a hard time to find the root cause of this issue and I would like to know if anyone here have some expirence with this type of issues.
Until know we have identified some conditions that change in the current process of these pieces:

The contaminated pieces were finished using a sand blasting process. the normal process should be polishing.
Contamination can not be removed from the parts.
This part are covered to be protected with a blue film, one of the teories is that the contamination came from the adhesive of the blue film, this happened due the surface after the sand blasting is more abrasive and the adhesive of the film came into the porous crated by this process.
I don´t know if this sound logical to you guys I´m not an expert on this area but what we know is the pieces leaves our company in good conditions, we have several inspections to validate this conditons and we never detect this issue.


Attached is a picture from the issue that we have, I really apreciate your help to get information about sanding process, anodizing on aluminum and contamination.