His approach relied on dramatic narrative. Boulanger often chose subjects from literature, including the works of Walter Scott and classical mythology. In Pegasus, he captured the energy of the mythical horse with bold lines. His depiction of Androcles and the Lion shows his interest in themes of mercy and nature. His work in lithography allowed him to experiment with light and shadow. He used these techniques to create moody scenes. This focus on storytelling through lithographs and oils set him apart from his contemporaries who favoured more rigid academic styles.

Modern collectors value Boulanger for the atmospheric quality of his prints. His scenes from La Jolie Fille de Perth or his depictions of monks in contemplation offer a sense of quiet drama. These works suit interiors that prioritise character and history. The connection to the Romantic movement provides a historical context that remains popular. His ability to balance literary themes with technical skill makes his prints a choice for those who appreciate art with a narrative background.