Assertion: carbon black | /r/CreatedBy | the oil furnace process
Facets:
value: since the mid-1970s
type: TEMPORAL
Source sentences:
text: Since the mid-1970s, most carbon black has been produced by the oil furnace process, which is most often referred to as furnace black.
text: Since the mid-1970s most carbon black has been produced by the oil furnace process, which is most often referred to as furnace black.