In the mid-1940s, Jackson Pollock underwent a significant transformation in his artistic approach, setting the stage for his later fame with the development of his iconic drip technique. This period was marked by several pivotal moments and works that highlighted his shift from a style influenced by murals, Native American art, and European modernism towards a more abstract and expressive form.

One key moment came with the commission from Peggy Guggenheim for a mural in the entry hall of her New York apartment. This work, titled Mural (1943), played a crucial role in Pollock's transition. The process and scale of the mural pushed him towards finding new means of expression, eventually leading him to experiment with pouring and dripping paint. By 1945, Pollock produced There Were Seven in Eight, a work where imagery began to be suppressed in favor of a tangled web of lines, hinting at the fully abstract style he was moving towards​ (The Art Story)​.

Pollock's experimentation with abstract expression became more pronounced in works such as Shimmering Substance (1946) and Full Fathom Five (1947). The latter, in particular, showcased his new technique of flinging and pouring paint, which allowed him to create endless webs of color. Pollock described his process as being more at ease when painting from the floor, feeling a part of the painting and being able to work from all sides, which was central to what critic Harold Rosenberg would later call "Action Painting"​ (The Art Story)​.

Despite the innovation and the energy of his new style, Pollock faced mixed reactions from the public and critics alike. While some recognized the power and originality of his work, others were shocked and incredulous. Commercial success and wider recognition were slow to come, though Pollock did gain a small circle of supporters during this time​ (The Art Story)​.

Pollock's work during the mid-1940s laid the foundation for the later success and influence he would achieve. His willingness to take risks and his innovative approaches to painting not only changed the course of American art but also inspired future generations of artists to explore new boundaries. His methods and the dramatic persona he projected contributed significantly to drawing attention to the broader group of Abstract Expressionists, ensuring his lasting legacy in the art world​ (ARTPIL)​.