His approach relied on clear, expressive lines that defined the character of his subjects. In his portrait of Elchanon Verveer, Holswilder depicts the painter examining a work with a critical eye. This piece bridges the gap between traditional painting and modern satire. His portraits of figures like Theophile de Bock capture the essence of the sitter with minimal strokes. He often worked with the firm of Mouton & Co. in The Hague to produce these prints. His work features a dry wit and an economy of line that avoids unnecessary detail.

Modern collectors value Holswilder for his ability to humanise the history of Dutch art. His prints provide a view into the studios and debates of a transformative era. The monochrome palette of his lithographs suits contemporary interiors that favour graphic clarity. These works are historical documents and pieces of sophisticated social commentary. They offer a personal connection to the art scene of the time.