In the early 1970's, Hamilton did a series of small paintings of harpy-like characters on foam-core, after discovering an abundant supply. He loved the smooth surface and was convinced that the quality paper and plastic core would last. He found his subjects by allowing their textured visages to remain from a dark field by over-painting the negative space around them with a rich blue. That process preceded and informed later paintings in which he covered an undercoat of abstract shapes and texture with lampblack, and then mined for his subjects and design by removing it.