Abstract: A refined fiber having an average length of 2 to 4 millimeter, a filler retention value of at least 18%, and a green strength value of at least 1.8 mJ/mm2 is described. The fiber is obtainable by a process wherein never dried yarn or sliver having a length of at least 1 meter is refined, by at least the step of feeding the yarn or sliver and a liquid into a refiner, which includes refiner fillings having a body surrounding a central hole, and at least one inlet for the yarn or sliver. Thus obtained fibrillated fiber may be used for making friction materials, gaskets, brake pads, or brake linings.