Lovely multiple!Note: Blair's post from 2008, Links possibly will not work
"Grande Consommation" (Great consumption) paper (also known as GC paper) was a poor quality paper used to produce French stamps (Merson and sower types) especially about 1916 - 1920. Its use resulted from the paper shortage during the War.
In official circular No 7740 (December 8, 1916), post-office employees learned that "the Administration is forced to use a less resistant paper for the printing of postage stamps." http://www.coppoweb.com/merson/images/7740.gif
These (GC) stamps were to be used on a priority basis. To distinguish the (GC) stamp sheets from normal stamp sheets, the letters GC (Great Consumption) were printed on some tabs in the top and bottom margins. http://www.coppoweb.com/merson/images/gc.gif
Of the Merson stamps, only the 40c, 45c, 50c and 1F values were printed on this type of paper.
Sometimes GC paper is white in colour (it should be examined with a magnifying glass to see the waste fibres
in its screen). Other times, GC paper is yellow, gray or chamois in colour.
Above all, specialist GC collectors seek stamps with a GC tab on chamois coloured paper.
To find the date of a stamp's issue, it is necessary to examine the paper and nuances of color which evolved
throughout the years. It should be known that, officially, there are 8 types of paper on which these stamps were printed. They go from very pure white to dull yellow, while passing through the reconstituted (fibres) paper types (especially in period of war 14-18 and right afterwards). This paper,
(GC) was of a poor quality, but it is highly sought today by collectors.
Blair Stannard (Canada)