of the bands a width of more than 4 mm is desirable even if not critical it will be appreciated that the bands which stop the cigarette from burning may also not be disposed at excessively great distances for which reason those distances are preferably below 20 mm as regards the applied amount of polymer simple tests make it possible to establish the values as from which the self extinguishing tendency is sufficient in that respect note is to be taken of the surprisingly established fact that a great reduction in porosity still does not automatically result in a substantially improved self extinguishing tendency it is only a further incorporation of material into the paper that leads to an almost abrupt increase in the self extinguishing tendency in this connection attention is directed more specifically to the examples set out hereinafter the way in which the polymer is introduced into the paper is not critical but intaglio printing has proven to be appropriate by virtue of using intaglio printing the bands have a high level of edge sharpness and it is not possible to detect a steady increase in the application of material from the edge to the centre the amount applied is adjusted by virtue of the etching depth the pattern repeat the level of concentration and the viscosity of the printing solution in order to improve the.