By 1973, Tetro was studying art by reading books and visiting museums. He never underwent formal art training or a desire to develop his own style, but he liked to paint and he liked copying from the masters. He found the exercise taught him more about the art, enabled him to understand why an artist had done a particular thing, which merely looking at a painting did not reveal. He learned about paper and canvas and experimented to find ways of producing craquelure, a characteristic of old paintings. Still a hobby, he began selling his copies at art fairs. He then began copying photographs and painting portraits. His hobby became a business and he became known within wealthy circles. The art market expanded in the 1980s and according to one Los Angeles art dealer, some people were more concerned about matching their carpet than they were about the authenticity of a painting. Reproductions were in demand and Tetro had a reputation for making flawless copies, even going so far as to travel to Europe to buy wooden stretchers and canvas particular to where a certain artist had worked. He has said that he never marketed his paintings and lithographs as originals and his business card read, "Tony Tetro. Art reproductions." Dealers told him his work would be sold to people who couldn't afford originals.