Pieter Hendrik Louis Gertenaar was born in Leiden and got his artistic education in The Hague. Before World War II, he worked at the Rotogravure Mij. in Leiden, at the same time as Marten Toonder. Before and during the War, he illustrated children's books for Mulder & Zn. in Amsterdam. He published his comic strip 'Ko Knaaggraag' in Katholieke Illustratie and Bravo between 1939 and 1941.
For a Swedish publisher, he made the strips 'Oeti-orang' and 'Hakki Plof en Archibald' in 1940. In 1941-42, he was working for Joop Geesink in Amsterdam, doing designs and backgrounds for puppet films. After the War, he went to work as a freelance advertising artist, working among others for the Schuitema brothers (CENTRA). He also took on painting.
Gertenaar cover for the book 'Vader leest voor' by Piet Broos