PRIOR TO THE 1960s the coatings industry enjoyed a somewhat predictable regulatory and economic environment. The paint formulator developing a solvent-based coating selected solvents on the basis of evaporation rate, solubility parameter, density, flammability, and, of course, cost. There was no apparent need to consider the relative photochemical reactivity of these materials, nor was there any appreciable incentive to reduce the solvent content of commercially acceptable coatings.