Fibrograms were obtained for cotton beards used in HVI testing after conditioning the beards in two different relative humidity environments, 30% and 65%, where the temperature was controlled to a nominal 70 degrees F. The differences in optical mass measurements for the fibrograms were negligibly small and close to the resolution of the optical system of the instrument. >From these results it was concluded that the optical measurements used as indirect indicators of mass for HVI strength measurements are relatively invariant to moisture content. A summary of the discussion and results for this paper is included in "A reference test for HVI strength measurements - implications for HVI testing", which is also included in these Proceedings.