Caprolactam, caprylolactam, and azacyclooctanone have been found to be equally effective as thiourea in stabilizing diazotype compositions and materials against pre-coupling, loss of shelf life, and dye image fading.
A diazo-type recording material comprising a support having thereon a recording layer comprising a photosensitive diazo compound enclosed in microcapsules, a coupling component which reacts with said diazo compound by heating at a basic pH to develop a color, and a 1-phenyl-3-pyrazolidone compound represented by the formula: ##STR1## wherein the substituents X, and R.sub.1 -R.sub.4 are defined in the specification.
