7016's/7018's/ Basic rods development over time

Hi all
A friend explained that "modern" dual-coat 7016's which leave the black glass slag have great user appeal (obviously) but are only made
possible by modern clean steels, where in times like the 1960's they needed the fully Basic rods to flux the much dirtier steels of the time.
The rods I'm free-issued on a project seem to be some fully Basic formulation intended for pipe-welding with perfect ground-to-silver prep. Even an expert welder agreed with me that he too would prototype on offcuts any critical under-time-pressure weld, given they have an "odd" handling and characteristics.
Anyone here with long experience like to enlighten us on 7016's/7018's past-and-present and how things have changed?
Best wishes, Rich Smith
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