Mentz studied at the Conservatoire of Music at the University of Stellenbosch from 1929-1931. After this she spent some time making Afrikaans records and teaching singing. In 1934 she went to Germany to study singing and acting and returned to South Africa in 1937.
After her return she did pioneering work in the cultural field. She was involved in various organisations that promoted the development of opera and was a member of PACTS’s opera committee and of the Johannesburg Music Society. Mentz was also a pioneer in the Afrikaans film genre and in theatre. She died in 1986.