His technique relied on a disciplined use of line to suggest texture and volume without the use of colour. Cathelin studied under Jacques-Philippe Le Bas, from whom he learned to balance the formal requirements of portraiture with a sense of atmospheric depth. He often worked from portraits by Joseph-Siffred Duplessis or Jean-Marc Nattier, focusing on the clarity of the facial features and the crispness of the sitters' attire. His engravings are characterised by a clean, architectural quality that avoids the cluttered ornamentation common in Rococo prints.

For the modern collector, Cathelin's prints provide a direct connection to the Enlightenment era through their monochrome compositions. These works provide a sense of historical weight and formal structure that complements contemporary interiors. The absence of colour focuses the eye on the geometry of the composition and the character of the subject. His portraits of philosophers and royalty provide a sophisticated aesthetic that functions as a quiet conversation piece in a study or a hallway.