Abstract: A color-developing sheet for pressure-sensitive recording sheets, said sheet comprising as a color-developing agent at least one 2,2'-bisphenolsulfone zinc salt selected from compounds of the general formula ##STR1## wherein R.sub.1 and R.sub.2 are identical or different, and represent a hydrogen atom, a halogen atom, an alkyl group containing 1 to 10 carbon atoms, a cycloalkyl group containing 3 to 10 carbon atoms, an aralkyl group containing 7 to 11 carbon atoms, or a phenyl group.

Abstract: Method of coloring a synthetic or semisynthetic organic high molecular weight material with a asymmetric thioindigoid compound having the formula ##SPC1##Wherein R.sub.1, R.sub.2 and R.sub.3 may be the same or different and are selected from the group consisting of a hydrogen atom, chlorine atom, lower alkyl group, lower alkoxy group, cyclohexyl group, phenyl group, benzyl group and styryl group, the benzene nucleus of the phenyl and benzyl group may be optionally substituted with a methyl group or chlorine atom, R.sub.1 and R.sub.2 may together form a tetramethylene ring, R.sub.4 is a hydrogen atom or methyl group with the proviso that R.sub.4 is a methyl group when R.sub.1, R.sub.2 and R.sub.3 are each a hydrogen atom and R.sub.4 is a hydrogen atom when R.sub.1 is a methyl group and R.sub.2 and R.sub.3 are each a hydrogen atom. The colored organic high molecular weight materials exhibit brilliant nuance with characteristic fluorescence.