Here is the best description of "additive painting" I have ever read-
"Traditional ways of seeing pictures could roughly be fitted into two categories: the additive and the overall. The additive relates part to part in larger and larger units which eventually add up to the entire painting... Systems of checks and balances inflect each other until the "right" moment halts the process and freezes the picture. The general effect- the additive synthesis- then clarifies the picture, within which little pictures happily reside. Instructed by the parent picture, the eye is invited to make its own compositions within, finding pictures within pictures, details within details, before withdrawing to lock everything in again with the full glance at the parent picture."
O'Doherty, B. (1973). American Masters- the Voice and the Myth. New York, NY: Random House. p.198