By early 1949 Mark Rothko's multiforms developed into the signature style; Rothko exhibited these new works at the Betty Parsons Gallery. For critic Harold Rosenberg, the paintings were nothing short of a revelation. Rothko had, after painting his first multiform, secluded himself to his home in East Hampton on Long Island. He invited only a select few, including Rosenberg, to view the new paintings. The discovery of his definitive form came at a period of great distress to the artist; his mother Kate died in October 1948.

It was at some point during that winter that Rothko happened upon the use of symmetrical rectangular blocks of two to three opposing or contrasting, yet complementary, colors, in which, for example, "the rectangles sometimes seem barely to coalesce out of the ground, concentrations of its substance. The green bar in Magenta, Black, Green on Orange, on the other hand, appears to vibrate against the orange around it, creating an optical flicker."

Additionally, for the next seven years, Rothko painted in oil only on large canvases with vertical formats. Very large-scale designs were used in order to overwhelm the viewer, or, in Rothko's words, to make the viewer feel “enveloped within” the painting. For some critics, the large size was an attempt to make up for a lack of substance. In retaliation, Rothko stated:

I realize that historically the function of painting large pictures is painting something very grandiose and pompous. The reason I paint them, however... is precisely because I want to be very intimate and human. To paint a small picture is to place yourself outside your experience, to look upon an experience as a stereopticon view or with a reducing glass. However you paint the larger picture, you are in it. It's not something you command!