Objectives: The purpose of this study was to determine the effect of hydration (human saliva) on lesions of varying severity and determine an optimal drying method to obtain reliable QLF readings. Methods: 10 previously extracted molars were selected, pumiced and coated with acid-resistant nail varnish leaving an exposed enamel window.  Teeth were placed into a demineralising solution for 7, 14 and 21 days.  Between each demineralising cycle the teeth were removed.  To test for reliability the teeth were placed in whole human saliva for 1 min and then QLF images were taken every 10 seconds (control cycle with no drying employed – bench air drying only). QLF images were taken in an ASA Class 1 darkroom, and room temperature was monitored throughout the experimental period. This sequence was repeated following a) compressed air drying (CAD) for 30 seconds, and 30 seconds application of cotton wool roll (CWR). Results: Control groups demonstrated the effect of hydration on QLF reliability; at 7 days (mean DQ 89.3(±33.2)) reliable results were obtained after 432.3 (±95.6) seconds.  Compressed air drying of saliva rinsed teeth reduced reliability time to 3.2((±7.6) seconds.  Cotton wool roll application produced reliable results in 110((±84.2) seconds.  As lesion severity increased (14 days mean DQ 115(±90.2), 21 days mean DQ 168.0(±120.7)) time to reach reliability significantly increased under control drying and CWT application (p<0.05). Time taken for CAD teeth to produce reliable results was not significantly different across the groups. Conclusions: Compressed air-drying for 30 seconds produces reliable results with saliva-hydrated lesions.  Future in vivo experiments will be required to determine if the air-drying can be reduced to a more clinically acceptable time.