Abstract: Cellulosic materials having a high capacity for absorption of water or aqus solutions, a large volume:weight ratio and a high resilience are produced by an acid-catalyzed cross-linking reaction in a reaction medium of low water content from a cellulosic or lignocellulosic material in the form of individual, substantially dehydrated, non-swollen and inter-fibre-bonds free fibres.

Abstract: A method of manufacture from a predetermined material, especially from a natural fibrous material and/or synthetic fibrous material of an article, in particular a sheet for printing or reproduction, which combines superior qualities of brightness, opacity, thermal stability, insolubility and lightness, said method consisting of laoding said material throughout its mass or superficially, with a filler product having a base of a methylene urea precipitate with a low degree of polymerization, obtained by the reaction of urea on formaldehyde in an acid medium.