Abstract: A radiation reactor for curing radiation curable products, coatings, inks, etc. The reactor has a plurality of radiation producing lamps carried in an enclosed chamber for directing radiation onto a coated substrate conveyed through the chamber. Supply and exhaust fans circulate ambient air through the chamber for cooling the chamber interior. A coolant carrying pipe is interposed between the lamps and the substrate conveyed to block at least a portion of the radiation field produced by the lamps for cooling the substrate surface.