Compositions for producing aminoplast products by means of melt processing consisting of: A) 95 to 99.9% by mass of solvent-free meltable polycondensates of melamine resins having molar masses ranging from 300 to 300 000; A) from 0.1 to 5% by mass of weak acids serving as thermoinducible curing agents consisting of: acidifiers of the blocked sulfonic acid type; aliphatic C4-C18 carboxylic acids; aromatic C7-C18 carboxylic acids; alkali salts or ammonium salts of phosphoric acid; C1-C12-alkyl esters or C2-C8-hydroxyalkyl esters of C7-C14 aromatic carboxylic acids or of inorganic acids; salts of melamine or of guanamines having C1-18 aliphatic carboxylic acids; anhydrides, half-esters or half-amides of C4-C20 dicarboxylic acids; half-esters or half-amides of copolymers consisting of ethylenically unsaturated C4-C20 dicarboxylic acid anhydrides and ethylenically unsaturated monomers of the C2-C20 olefin type and/or C8-C20 vinyl aromatic compounds; and/or salts of C1-C12-alkyl amines or alkanolamines having C1-C18 aliphatic, C7-C14 aromatic or alkylaromatic carboxylic acids and inorganic acids of the hydrochloric acid, sulphuric acid or phosphoric acid type, and; B) optionally up to 400% by mass of fillers and or reinforcing fibers, up to 30% by mass of additional reactive polymers of the ethylene copolymer, maleic anhyudride copolymer, modified maleic anhydride copolymer, poly(meth)acrylate, polyamide, polyester and/or polyurethane type, and up to 4% by mass, each time with regard to the polycondensates of melamine resins, of stabilizes, UV absorbers and/or auxiliary agents. These inventive compositions can be processed by means of melt processing into products such as panels, coated supporting materials, profiled pieces, pipes, injection-molded articles, fibrous products and laminates.