That raises interesting questions...
First, why would the die (not the press, just the die) be used for multiple metals? A hood is a fairly large piece and I would have assumed it is stamped individually with its own die, or on a die with multiple identical parts (as in multiple hoods). Also, wouldn’t aluminum and steel parts need different stamping pressure, etc...? And, since Ford doesn’t make a steel version of this hood, if it was stamped individually, there should then be no transfer of ferrous material from previously stamped parts, as the die would only be used for this one item. Does that mean the die for the hood includes other parts that are steel, say fenders or hoods for other products, or is the die itself (which is presumably some manner of ferrous metal) transferring the flakes?
Second, if it is coming from the stamping process, is it more common during certain portions of the run? For example, would more transfer early in the use of a new die and then taper off, or vice versa as the die wore out?
Third, if it is from the stamping process, why does it seem to mainly impact the hood lip? Is it because of the crimp trapping the ferrous material? Is it because that area is exposed to more residual moisture?
Finally, if it is from the stamping process, will replacing the hood actually solve the problem? If the hoods are stamped in the same process and have an equal chance of getting ferrous material on them, one would assume the risk of the issue resuming was similar to the original risk. Has Ford come up with a way to remove the material in the prep instructions given to dealers/subbed body shops?