Complex sentence: At the beginning of his career as an illustrator, Bauer was hindered by the printing technique at that time: printing with all colors was very expensive, and therefore not normally done, so he had to settle for one color plus black.
Split into simpler sentences: At the beginning of his career, Bauer had to adapt his illustrations to the printing technique at that time. Printing with all colors was expensive, and therefore not normally done, so the illustrations were made in one color plus black.