Is it grammatically correct to say here "the results of which"?
Is it grammatically correct to say here "the results of which"?

Adhesion tests were performed on the surfaces that were either not checked during the initial inspection or the results of which were determined as not satisfactory.

Question

Is it grammatically correct to say here "the results of which"?
Is it grammatically correct to say here "the results of which"?

Adhesion tests were performed on the surfaces that were either not checked during the initial inspection or the results of which were determined as not satisfactory.

Answer

It is a good sentence, but it might be a bit more clear if you said: Adhesion tests were performed on the surfaces that were either not checked during the initial inspection or that had test results which were unsatisfactory.

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Yes, excellent sentence!

I recommend making these minor changes:
Adhesion tests were performed on the surfaces that were either not checked during the initial inspection or the results of which were determined to be unsatisfactory.

Answer

In my opinion not really:

Adhesion tests performed on the surfaces were either not checked during the initial inspection or the results were not satisfactory.

Answer

Yes.

Answer

I would say that it's heavily implied that you're talking about the results already.

"Adhesion tests were performed on the surfaces that either weren't checked during the initial inspection, or which were determined to be unsatisfactory."