His association with the Fluxus movement was played down by Isaacson, who held European classical tradition in high regard, although his experimental and minimalist compositions drew inevitable comparison.
It was at James River High that Isaacson began a study of his synesthesia, a mild case of which he had correctly diagnosed, and his own emotional response to color.
His private, experimental, compositions, "doodled" pieces consisting of finely inked lines on a conventional stave, took on a more powerful and expressive form and, in 1950, by now a lecturer at Virginia State University, he produced the first of his "Colortone" series.
A move to Mannes College, New York, in 1951 encouraged fresh creativity, and by 1958 Isaacson had produced a further 8 Colortone pieces, the first of his four "Abstractions", and "For Diego Rivera", a tribute to the Mexican artist, who had died in November the previous year.
Isaacson had put aside sheet music, favoring slides, projections and abstract painting, and would not use printed scores again until his "Chromatics No.