Kinetics of chromate reduction by ferrous ions derived from hematite and biotite at 25 degrees C

A heat-applying recording head to image selected microsize points of a heat imageable recording material comprises a heating wire support body having a thin recording material facing end with longitudinally closed spaced, transversely extending notches therein which form wire-positioning recesses which terminate in respective aligned edges to face the recording material. Fine threads of heating wire material extend in said notches and respectively bend around the aligned edges to extend along opposite faces of the support body. The threads of heating wire are substantially thicker than the depth of the notches so as to project substantially beyond the support body. The heating wire-forming threads along at least one of the faces of the support body to diverge progressively in a direction away from the recording material facing end of the support body and extend to relatively widely spaced current feeding terminal points. The threads of heating wire material at points near the points where they bend around the aligned support body edges are enveloped and electrically shunted by a low resistance material. The recording material facing end of the support body with the fine threads of heating wire material supported thereon are encapsulated in a body of heat sink-forming material which extends contiguous to but is spaced from the portions of said support body where the threads of heating wire material bend around the aligned edges thereof.