In 1910 he opened a large factory in Nanterre, now part of Paris, and published postcards with the marques JC and Triomph - often both on the card. In 1913 his directory entry, though in the postcards section, merely promoted cheap items for fairgounds. In the 1914 directory (his entry in 1918 is identical) he also listed the marques S.I.P., Lilas, Phébus, Astra, Cloche, Royal, Circé, U.D.D, Hecla, and P.H.B. but he may have been just the printer and/or seller of some these cards as E Rabus was the publisher of many of them at this time. (Triomphe, Lilas, Circé and P.H.B. cards are shown on this web site under E Rabus, UDD has its own entry and JC/Triomphe and the rest are here). He also re-issued cards previously issued as ASTOR, keeping the card number and overwriting the original logo with JC. He did a similar thing with with some La Penseé cards - see under that marque. During WW1 he issued some cards with "J Courcier" on the face. His later directory entries under the postcards category are very much shrunk, perhaps because by then he was primarily a printer.
There is a .pdf about J.C. Paris at:
http://histoire-nanterre.org/wp-content/uploads/2016/06/NI_SHN_411.pdf.