Thermoforming is the most commonly used forming process in plastics engineering. All used thermoplastics need to have a sufficient elasticity in order to be reshaped well. Conventional polyamide 6 cannot be used for this application because of its low molecular weight and low stability near the melting point. Cast polyamide 6, which is used for direct polymerization of molded parts, in contrast, has got high molecular weights. Because of sprues and post-processing, a larger amount of scrap is produced. It offers the opportunity to produce high molecular weight recyclates. By adding specific amounts of different carboxylic acids, it is possible to adjust the molecular weight and thus the flowing behavior. Stiffness and strength are not affected by said additives. The thermoforming behavior depends on the viscosity and the molecular weight respectively of the material. Highly viscous recyclates are reshaped well, while materials having lower viscosities are showing uneven shaping.