A novel photoimageable system for a two-chemistry system containing liquid photoreactive asymmetric acrylate compound containing sulfur, aromatic moieties, and optionally bromine, and an aluminum salt compound is disclosed. The photoimageable system has high dynamic range (M/#) and sensitivity and unexpectedly high temperature and high humidity resistance. The photoimageable system retains its dynamic range when exposed to 60.degree. C. for 4 weeks while a composition without the aluminum salt compound lost 75% of its dynamic range under similar exposure conditions. In one embodiment, 2-10 weight % of a thio-butylacrylate dissolved in a two-component urethane matrix containing 0.002 to 1 weight % of the aluminum salt compound showed a dynamic range of greater than 5 for a 200 microns thick sample and retained more than 80% of the dynamic range after 4 weeks exposure at 60.degree. C.