After The Black Paintings, Neuman began exploring the expressive nature of color. This dramatic shift was influenced by his time studying in Barcelona as a Guggenheim Fellow. His Barcelona Series, begun in 1956, is defined by his attempts to create a universally relevant style of art, which, in this case, captured his impressions of the motion and light of the narrow streets of Old Barcelona. With the advent of the 1960s, Neuman explored the potential of abstraction more fervently than ever. During this decade, he created his Abstract Landscape, Abstract Figures and his Diamond Canvas Series before experimenting further with the use of symbols.
In 1980, Neuman began the Lame Deer Series. Lame Deer was inspired by a visit to a Native American reservation close to the Battle of Little Big Horn in Lame Deer, Montana. Visiting the historic site spurred Neuman to visually relate the Western American landscape in a way he felt had not been done before. History is hidden in each vividly chromatic landscape where the most prominent symbol is the teepee— each has the skin stripped away, and resembles "…drawings on a cave wall, remnants of a people continually in flight.” Ultimately, the Lame Deer series was meant to bring attention to the plight of the Native Americans. As the 1980s progressed, Neuman explored new avenues of visual expression. His Rose Paintings, begun in 1982, are monochromatic, sumptuous and textural landscapes, using the applied technique of tachisme. Meanwhile, the Voyage Series, begun in 1986, saw Neuman exploring the symbolism of knots, often seen in Celtic, Viking and Moorish art, as a metaphor for travelling through life. Neuman's new works, created during the 1990s to present day, are a visual melting pot of many of his earlier series including Alhambra, Barcelona and Rose Paintings. The gestural compositions and broad flat panes of color look back to his earliest days as an Abstract Expressionist. Each work is still distinct from what has come before and begins to define what will come next.Wikipedia