I'm kind of surprised that Leonardo said that, because most of those old-timey guys tended to use a red ground under their paintings, kind of like gilders use under gold.

Hmmm...

This is incorrect: DaVinci was referring to the base for creating colored paints, not primer. For the best results with certain colors when painting your walls and ceilings, it's smart to tint your primer first.... Just ask your paint dealer.

i like the painting guy. hired painters are never this cute.