So a rotor made from an iron with lots of impurities, a non-homogeneous/incomplete blend will be just as good as a rotor made from a properly created "good" iron?

Yes, if there is a mistake in the metallic make-up of something it is more than likely the foundry's fault, however the result of that screw-up will show up in the molecular structure/composition of the end product. Blaming the foundry vs. blaming the metallurgy is semantics when it comes to the end user.

For example, I have a pasta sauce that is too salty to eat. It is too salty because it has too much salt in it. The fact that I'm the one that put too much salt in it doesn't take anything away from the fact that it has too much salt in it - the end result is that it has too much salt in it. Who put too much salt in it is irrelevant when it comes to the saltiness.

Further more, iron rotors are hardened during the casting process by controlling the rate of cooling. If you cool them too quickly, they'll be harder and more brittle. If you cool them too slowly, they'll be softer.

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A.S.E Tech A1,A6,A7,A8 & MVAC 609 + EPA 608

Unless stated otherwise, any question I ask is about my greymarket 1985 380SEL.