ity is approximately between 15-18 secs. at 100 F. The paper or cloth is saturated with this composition in the usual manner of impregnation and, when properly dried, is backsized with a material which takes pencil or ink transfer impressions and is preferably made up as a solution of glue or a cellulose derivative such as ethyl cellulose, cellulose acetate, cellulose xanthate or cellulose nitrate