An imaging system employs method of labeling orthogonal images. 99 to 10% by weight of at least one \u03b1,\u03b2-ethylenically unsaturated compound with at least one cationogenic andor cationic group per molecule, 0 to less than 25% by weight of at least one monoethylenically unsaturated amide-group-containing compound different from a) and also 0. A release element in the passageway of the hub is positioned to block fluid-tight engagement of the frusto-conically-shaped tip with the cavity of the hub. The retainer bar carries a helically wound spring that secures one end of the spring for resistance to rotation about the axis of the bar.