Yerka studied art for a short time at University, but then learnt from direct study of Northern European masters, the Van Eycks, Dierck Bouts, Robert Campin, Bosch, and surrealists such as Magritte.
He did his first painting of his life a year before going to college, where he began studying graphics. His instructors always tried to get him to paint in the more contemporary abstract style, and move away from his fascination with realism. He saw this as an attempt to stifle his own creative style and steadfastly refused to fall in line. Eventually, his teachers relented.
His paintings are acrylic on canvas and carefully rendered, using images from his childhood, including his grandmother's kitchen. He also includes odd beasts and whimsical landscapes. He comments, "For me, the 1950s were a kind of Golden Age ... If I were, for instance, to paint a computer, it would definitely have a pre-war aesthetic to it."
Yerka's work has been exhibited in Poland, Germany, Monaco, France, and the United States. His works are also in Polish art museums.