After completing his military career, in 1790 Robert became an indentured clerk at one of the Didot family's Paris publishing houses. First working under Saint-Léger Didot as a clerk, he later switched to a position as "inspector of personnel" at Pierre-François Didot's hand paper-making factory in Corbeil-Essonnes in the suberbs of Paris. This establishment had a history dating back to 1355, and supplied paper to the Ministry of Finance for currency manufacture. Both Robert and Didot grew impatient with the quarrelling workers, vatmen, couchers, and laymen, so Robert was motivated to find a way to mechanize the labor-intensive process of making paper by hand.
Prior to 1798, paper was made one sheet at a time, by dipping a rectangular frame or mould with a screen bottom into a vat of pulp. The frame was removed from the vat, and the water was pressed out of the pulp. The remaining pulp was allowed to dry; the frame could not be re-used until the previous sheet of paper was removed from it. Robert's construction had a moving screen belt that would receive a continuous flow of stock and deliver an unbroken sheet of wet paper to a pair of squeeze rolls. As the continuous strip of wet paper came off the machine it was manually hung over a series of cables or bars to dry. This continuous, unbroken sheet of paper later had to be cut. An advantage of making continous sheets was that it the large sheets could be printed for wallpaper.
Robert applied for a French patent for his machine on September 9, 1798; it was granted in 1799. However, because of disagreements between Robert and his partners, St. Leger and François Didot, and also because of financial disruptions caused by the French Revolution, François Didot attempted to have it developed in England, sending his English brother-in-law, John Gamble, to London to develop the technology.
In 1801 John Gamble, of Leicester Square, Middlesex County (now London), received British patent No. 2487 for an "Invention of Making Paper in single Sheets, without Seam or Joining, from One to Twelve Feet and upwards Wide, and from One to Forty-five Feet and upwards in Length." Gamble's specification was essentially a translation of Robert's patent. The title of the specification, with its emphasis on the production of very large sheets, indicates that the original market for the product was expected to be wallpaper. Earlier that year Gamble returned to France to obtain drawings of the machine for the patent specification. He also arranged to have Robert's working model of the machine sent to England so that improvements could be made.
In 1976 Janet Fourdinier sold Robert's original drawings of his papermaking machine at auction. These were acquired by collector and papermaking historian Leonard Schlosser. After Schlosser's death the drawings were reproduced in color in their original size and published by Henry Morris of the Bird & Bull Press with an explanatory introduction in Nicolas Louis Robert and his Endless Wire Pamaking Machine with Facsimiles of the Inventor's Original Drawings of the first Paper Machine, Including a chapter on the papermaking historian Leonard B. Schosser (2000).
Clapperton, The Paper-making Machine. Its Invention, Evolution and Development (1967) 15-33.