His career and that of his son, François-Charles Joullain (died 1790), expanded from their initial roles as engravers and printmakers to merchants of paintings and publishers.
He became a noted publisher for producing books of engravings which were of high quality and very popular in the 18th century and a prominent art dealer in Paris.
For this, he produced a series depicting Riccoboni's own comic actors as the appeared on the stage at the time and also added images of historical counterparts.
Joullain seized this opportunity to abandon his career as engraver and illustrator, for the more lucrative practice of printseller and dealer in old master drawings.
[12] For instance, he purchased four volumes of a work dedicated to documenting historical fashions with engravings by Dezallier, in an effort to avoid having the collection broken up for resale.
[18] Finally, his son was instrumental in establishing a systematic approach to the documentation of artworks with Répertoire de tableaux: dessins et estampes , ouvrage utile aux amateurs (1783); a work in which he started to record the prices and provenances of major paintings sold in the previous decade, but left unfinished.