http://escape-maps.com/history_of_ww...f_contents.htm
http://escape-maps.com/map_list_hist..._us_tissue.htm
http://www.travellady.com/Issues/Dec...ofSilkMaps.htm
"The silk maps were developed by MI9, the escape and evasion wing of British Military Intelligence. The cartography was supplied by the Bartholomew map company, with all copyrights waived in support of the war effort. Waddington plc, known for games such as Monopoly, employed its experience of detailed printing on fabric to print the maps with the required detail. The silk was specially treated for durability and the impressive printing clarity was achieved by adding pectin to the ink."
http://www.matrixgames.com/newsletter/march2008.html