The clamps initially used to hold fibers during the strength test allowed fibers to slip after 5000 breaks on our instrument. Cleaning did not help this first set of clamps. Another set of clamps were used to make 12,500 breaks before slight slippage occurred. Cleaning of the clamps brought them back in the vicinity of their original level. A slight modification in the clamps has so far allowed over 40,000 breaks without cleaning the surfaces while maintaining a close proximity to the original level. This modification and narrowing the sample thickness range allowed differentiation of breeder samples which could not previously be determined with either HVI. The possible reason for strength increasing with sample thickness is explained. The span length region at which the breaks occur on the Stelometer is descendent upon the length of the cotton. Longer varieties are broken closer to the tip of the beard than shorter varieties. Cleaning of an original type set of clamps that have been well behaved for a number of breaks increases the strength values obtained by approximately 20%. The optical attenuation used to determine mass and length appears to become increasingly saturated with thickness of sample. As the Instron rate of extension is increased, the average tenacity does not appear to change, but increases slightly for some varieties while decreasing slightly for others. Slopes of strength versus relative humidity on the HVI appear to be about the same indicating that they are relatively parallel for the calibration cottons, but become more diverse when our library cottons are run.