Primitive paintings in need of refinement (5,4)

I believe the answer is:

crude oils

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'in need of refinement' is the definition.
I can't tell whether this definition defines the answer.

'primitive paintings' is the wordplay.
'primitive' becomes 'crude' (synonyms).
'paintings' becomes 'oils' (oil paintings).
'crude'+'oils'='CRUDE OILS'

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I've seen this clue in The Globe and Mail.

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