A withered hand resulting from an old battle wound did not prevent Etienne-Henri Le Guay from becoming a porcelain gilder at the Vincennes Porcelain Manufactory. In 1742 he joined the factory, where he polished and glazed the porcelain wares before joining the king's regiment for six years. Only through the personal intercession of Madame de Pompadour, who arranged that he should be loaned some money to buy his release from the army, was he allowed to return to Vincennes, later the Sèvres porcelain manufactory.
From 1773, Le Guay's mark, a scrolling LGin gold, appears on numerous types of forms, from vases to vessels for tea. He also gilded many special porcelain commissions for Louis XVI, Marie-Antoinette, and the Russian empress Catherine the Great. Le Guay's salary also reflected his valued position, as he started at fifty livresper month and increased to ninety.