In 1787, five years after Porthaux went into business, the composer and renowned bassoonist of his time, Étienne Ozi, furthered the maker's career by recommending his instruments in an instruction book entitled Méthode nouvelle et raisonnée pour le basson.

This example features six keys, including a speaker key, which came into use soon after 1800 to facilitate the "speaking" of the highest notes. Its bearing arrangement is unusual in that the keys are tucked over an oblong socket in the wood instead of having metal capsules. The bassoon was acquired with its original extra wing joint (for lower pitch) and original bocal (curved metal tube), as well as two boxes of period reeds. The survival of such a complete set in its original case is rare.

Porthaux's bassoon foreshadowed what later in the nineteenth century came to be called the French, as opposed to the German, bassoon, featuring a colorful, slender, and slightly nasal sound; long tenons; characteristic key flaps; and a particular turning profile of the bell section.