A layer comprised of a radiation-polymerizable mixture containing (a) a first compound capable of undergoing free radical polymerization, the first compound containing at least two terminal ethylenically unsaturated groups and having a boiling point above 100.degree. C. under atmospheric pressure, (b) a second compound capable of initiating the polymerization of the first compound when exposed to actinic radiation, and (c) a water-insoluble copolymer which is soluble in aqueous alkaline solutions and which comprises (c1) an .alpha..beta.-unsaturated aliphatic carboxylic acid and (c2) an alkyl methacrylate having at least 4 carbon atoms in the alkyl group, wherein the copolymer has a mean molecular weight in the range from about 50,000 to 200,000 possesses high flexiblity and resilience in both unexposed and exposed states. The mixture is particularly suitable for use as dry resist material for the tenting technique in printed circuit board production.