Zak arrived in Australia in 1980 as a political refugee. He brought considerable professional training and experience in illustration, having trained in Prague for three years as a children's book illustrator. He has also worked as a theatre designer, art restorer, and film animator. Zak's father was an internationally known architect and this influence is sometimes evident in the architectural detail in his work.
Holden also suggests that Zak has been influenced by the renowned American illustrator, Maurice Sendak, and Mordillo. During the mid-1970s, Zak held exhibitions of his lithographs in Brno and of drawings in Prague.