polymeric fibers have been systematically added to the refractory castables formulations in order to reduce the risks of explosive spalling during the drying and first heat-up process. after fibers melt, permeable paths are generated, reducing the vapor pressure and increasing the drying rate. the polypropylene fibers are traditionally employed in this technique and modify permeability at 165 oc. to optimize the performance of these fibers, their melting point must be reduced bellow to 100 oc. as there is not great availability of fibers with this requirement, a melt-spinning equipment and a new generation of fibers were developed, based on a careful choice of polymers and copolymers, as well as their composition and physical and chemical properties. fibers with geometry similar to the conventional ones were produced and their performance as drying additives were evaluated, presenting better results than the conventional polypropylene ones.