A technique for the tensile testing of single wood pulp fibers in air and in water is described. Successive loading-unloading tests with increasing loads showed that the immediate elastic recovery of the wood pulp fibers was a linear function of the removed load. The slope of the straight line is inversely proportional to the rigidity of the fibers. Creep curves were recorded at 50% relative humidity and in water. As the testing method involves the measurement of the elastic recovery, the effect on the strain of the irreversible extension of microcompressions and crimps is eliminated. The method presented in this paper may therefore be more accurate for the determination of rigidity than those which evaluate rigidity from stress-strain curves. The tensile testing technique was critically examined, with special emphasis on the reliability of the adhesive used in attaching the fibers to the testing apparatus. The calculated elastic moduli and the creep behavior agreed well with literature data
