A thermally processed image forming material containing elsewhere on a
support a reducing agent, a binder and non-photosensitive fatty silver
salt grains was disclosed, in which (1) the non-photosensitive fatty acid
silver salt grains are prepared by mixing and reacting a silver
ion-containing solution, the solvent of which being water or a mixture of
water and an organic solvent, with a solution of a fatty acid alkali metal
salt, the solvent of which being water, an organic solvent, or a mixture
of water and an organic solvent, in a closed mixing means, or (2) the
non-photosensitive fatty acid silver salt grains are prepared by
micro-dispersing the reaction mixture at an operating pressure of 1,800
kg/cm.sup.2 or above using a ultrahigh pressure dispersion apparatus. Such
thermally processed image forming material is excellent in the coated
surface quality, and can afford an image which is low in fog and high in
Dmax (maximum density).
