Disclosed is a method for producing single- or multi-layered fiber performs by the TFP process with fiber strands which are aligned substantially such that they are oriented with the flux of force, are laid on at least one backing layer and are attached by at least one fixing thread. After completion of the TFP process, at least one fiber preform is introduced into a fixing device to secure the position of the fiber strands and the fixing threads and/or the backing layers are at least partially removed. As a result of the preferably complete removal of the fixing threads and/or the backing layer from the fiber preform, the latter has virtually ideal mechanical, quasi isotropic properties. In a preferred variant, the fixing threads and/or the backing layers are formed by a water-soluble material, so that they can be completely dissolved by water as the solvent and flushed out.