Jerry Saltz at New York Magazine:
His huge Technicolor paintings, draped without frames, crossed over into sculpture — tabernacles to fearlessness and radicality. Hung from the ceilings or tacked to the walls, they looked like canvas mountain ranges or gigantic tents and huts, marching cities on the plain.
The epic scale of these paintings intensified the minds of viewers. They felt fun, thrilling, revolutionary — an advanced vocabulary of familiar things acting strangely. Here were paintings that were storm-blown into swooping, cresting shapes, great oceanic structures that were metaphors for the sublime. You could not turn away. By his 30s, Gilliam had already cracked the code of the canon. He took color-field and stain painting, Ab Ex all-over-ness, and cross-wired it with the shaped paintings of the early 1960s, which bent and broke through the traditional rectangular frame.
more here.