He is noted for his alteration of preexisting media—such as old books, maps, record albums, and cassette tapes—to create new, transformed works of visual fine art.
He then began to make work by repeatedly pasting newspapers and book pages to canvas and tearing off pieces, leaving behind layered fragments.
Dettmer explains: "Old books, records, tapes, maps, and other media frequently fall into a realm that too much of today's art occupies.
As he cuts away unwanted material with knives, tweezers and surgical tools, Dettmer stabilizes the remaining paper with a varnish.
Dettmer has subsequently augmented his process by folding, bending, rolling, or stacking one or more books before sealing and cutting them or, in some instances, sanding them to create a variety of forms.
Other notable examples of media transformed by Dettmer include music cassette tapes melted and formed into a life-sized human skeleton (Tyson 2007) and various animal skulls; cut and layered highway maps of the United States and the Middle East (Packer 2005) and three-dimensional map sculptures; VHS videotapes of gangster movies unraveled and formed into funeral flower arrangements; and a controversial reconfiguration of audio excerpts from George W. Bush's 2002 State of the Union Address.
His work can be found in public and private collections in the United States, Latin America, Europe, Australia, and Asia.