In his autobiography Blass wrote that the margins in his school books were filled with sketches of Hollywood-inspired fashions instead of notes. At fifteen, he began sewing, selling evening gowns for $25 each to a New York manufacturer. At 17 he had saved up enough money to move to Manhattan and study fashion. He excelled in his fashion studies immediately and at 18 was the first male to win Mademoiselle’s Design for Living award. He spent his salary of $30 a week on clothing, shoes, and elegant meals.
In 1942 Blass enlisted in the army. He was assigned to the 603rd Camouflage Battalion with a group of writers, artists, sound engineers, theater technicians, and other creative professionals. Their mission was to fool the German Army into believing the Allies were positioned in fake locations. They did this by using recordings, dummy tanks, and other false materials. The US Camouflage Battalion proved to be more successful than the European Camouflage Battalion.
Blass’ designs are best known for being wearable. In a time when other designers were designing clothes which were known more for being a work of art, Blass was designing clothing which even everyday women could wear day or night. According to Ellin Saltzman in the New York Times, "He took American sportswear to its highest level…giving it a clean, modern, impeccable style… He, probably more than any designer knew his customer and understood her."
Beginning in 1976, and continuing until 1989, Blass lent his talents to the Ford Motor Company for an exclusive edition of their Continental Mark series of automotive products. In 1976 he shared model configurations with Emilio Pucci, Hubert de Givenchy, and Cartier. Each year, as goes true fashion, the interior and exterior color combinations would be updated. One of the most popular was the 1979 edition honoring a nautical theme, as did the Blass logo of the time. Small anchors were incorporated into the exterior accent striping and interior accents within the Blass back-to-back "B" design theme. A truly unique feature of this model, and the 1980 through 1983 Mark series Blass models, was a "carriage roof" giving a convertible top look to the cars. After 1983, the Blass edition became just a unique color option with rear quarter window model designations and a few features that were options on the standard model.