Traditional medium-pressure mercury (Hg) lamps produce a wide spectrum of radiation, including significant emissions in the ultraviolet region, specifically UVC, UVB, UVA and UVV. This spectral breadth allows for the selection of photoinitiator(s) to optimize the cure of acrylate-based inks, coatings, adhesives, sealants and composites according to the type and intensity of the light source, as well as accounting for species within the formulation that block and/or absorb UV light (e.g., pigments and fillers).
These traditional Hg lamps yield 70-75% radiation in non-useful wavelengths, most notably high-energy infrared light that produces significant heat. The need to keep typical Hg lamps cool requires voluminous airflow, and, thus, additional energy. Such high airflow eliminates the practicality of using inert gas to improve surface cure. (Costly inert gas would be constantly exhausted along with cooling air.)