In 1946, Eyring became Dean of the Graduate School at the University of Utah, and encouraged Cook to join him there, arranging an offer of Full Professor of Metallurgy with tenure in 1947. While there he continued working with industry, serving as a consultant to more than 100 companies throughout the world. He was asked to work with a committee of scientists investigating the Texas City disaster of 1947, in which two shiploads of ammonium nitrate fertilizer exploded in the Galveston, Texas harbor, killing more than 600, including 300 scientists at a Monsanto facility there.

Cook's greatest invention came in December 1956 , when he discovered a new type of blasting agent, the "slurry explosive," an unusual mixture of ammonium nitrate, aluminum powder and water. The invention converted the commercial explosives industry from using more dangerous dry explosives like dynamite to "safe slurry." The invention led to Cook forming with others IRECO, a company to commercialize slurry explosives. Cook left the University of Utah and spent most of the 1960s as a President of the company, until 1972 when he was succeeded by his oldest son, M. Garfield Cook. But proxy battles pushed Cook out of the company by 1974.