Hellers letter was forwarded by Eleanor Roosevelt to FBI director J. Edgar Hoover, who in turn consulted with the director of the alien enemy control unit. This resulted in Hansgirg being released under parole by Theodore Dreier, the treasurer of Black Mountain College, a progressive experimental educational community in North Carolina. Hansgirg was appointed as chemistry professor to replace Charles Lindsley, who took a position with the US department of defense doing research for the war department in 1942. This decision was taken on the advice of Austrian scientist Karl Terzaghi. Hansgirgs parolee sponsorship was transferred in 1943 to Dr. W. R. Wunsch, another employee at Black Mountain College, and then to Isaac Van Horn in July 1944.
At Black Mountain College, Hansgirg combined teaching of chemistry and physics with research and business activities. In 1943, an extension was added to the schools science building to make room for a photography darkroom and for Hansgirgs experiments in extracting magnesium from olivine, a locally abundant mineral. Later in the same year, he developed a modified method of magnesium production that used calcium carbide as a reducing agent. Hansgirg created and applied for patents under the name of the North Carolina Magnesium Development Corporation, and gave 20% of the shares of this business to the college.
Although many of his colleagues had fled Europe during the rise of fascism, Hansgirg was the only Black Mountain College community member with "enemy alien" status. He was known for letting the college community use his grand piano, his organ, his photographic equipment and his extensive collection of opera recordings. He was also one of the few faculty with personal wealth, and provided champagne and strawberries for special celebrations.
In September 1948, the building that housed Hansgirgs equipment and experiments burned down in a fire rumored to have been the result of a fellow faculty members vodka still.