By applying glazed layers in combination with hard-edge painted lines, Mullen creates layered images that figuratively communicate abstract concepts. When creating illusionistic forms he can, to some degree, illustrate an abstract idea or phenomenon, turning abstraction on its head. As a devoted craftsman who meticulously creates all of his work without digital or mechanical aids, he still manages to create the impression of reproducibility, which is precisely what he seeks to highlight in an era of mass consumption.