At the conclusion of his studies and training, Isaac returned home to Lexington to teach at Keene High School. There he worked from 1897 to 1902. He also opened his first art studio, where he made plaster parts of human anatomy for schools and medical uses. In 1907 Isaac relocated to Washington, DC, where began making sculpture busts, including those of abolitionist Frederick Douglass, university president Booker T. Washington, poet Paul L. Dunbar, and scholar W.E.B. Dubois.
In 1912, the accomplished teacher and talented artist married Ettic Ramplin of South Boston, Virginia. Sadly, she died early in their marriage from complications in childbirth. Following Ettic's death, Isaac established a course in ceramics at Branch Normal College, now known as the University of Arkansas, Pine Bluff. He taught there and at a high school in Pine Bluff until 1937. In 1926, Isaac married his second wife, Umer George Porter. The couple moved to Tuskegee, Alabama, in 1937 to inaugurate the ceramics department at Tuskegee University. Shortly thereafter, Umer earned a degree from Tuskegee and became Isaac’s assistant.
The remarkable educator made an important contribution to the art world in 1945 when he developed Alabama kaolin clay as a medium, and he became the first artist on record to “make the clay behave.” The following year, Isaac was commissioned by the Fine Arts Commission of the United States Mint to design a half dollar coin using Booker T. Washington as the face and subject. In 1950 he was commissioned to make another coin, this time combining the images of both Booker T. Washington and George Washington Carver.
During the summer of 1947, Hathaway broke a significant racial barrier when he introduced ceramics at the all-white Auburn Polytechnic Institute, now known as Auburn University. In 1947, Isaac and Umer relocated to Montgomery, Alabama, where Isaac became the director of ceramics at Alabama State College. He worked there until his retirement in 1963.
Throughout his life, Professor Hathaway received many awards, including honorary degrees, doctorates, or fine arts awards from various colleges and universities where he helped introduce ceramics as a field of study. This chalkboard champion and amazing artist passed away at his home in Tuskegee, Alabama, on March 12, 1967.