Abstract: Prepregs are fabricated in a substantially horizontal treatment chamber by heat treating a material web impregnated with a thermosetting resin. In this treatment chamber, the material web is subjected to blowing directed toward the material web and held thereby in suspension. The blowing air heats the material web and dilutes and conveys away solvent vapors. Alternately with zones of blowing directed toward the material web, there are arranged radiant-heating zones.