Effect of Wilhelmy Balance Parameters on Fluid Holding Time

EFFECT OF WILHELMY BALANCE PARAMETERS ON FLUID HOLDING TIME 

Wilhelmy plate wetting parameters, such as plate velocity during immersion or emersion and halting the motion of the plate after immersion or emersion, have been shown to alfect the intrinsic hysteresis, which consequently affects the overall shape of the force loop [3]. These wetting parameters were found to affect FHT differently depending on whether pure water or an aqueous artificial tear solution was employed as the wetting medium. 

The FHT measured by the Wilhelmy balance method can be effectively used to compare the liquid holding capabilities of different surfaces. The value of FHT depends on the experimental parameters and cannot be used in an absolute sense. In general, the aqueous film stability is obtained when spontaneous wetting occurs on imperturbable surfaces. However, moderately hydrophilic and possibly even some hydrophobic surfaces that are perturbable by water were found to be capable of holding continuous films of water. Multicomponent fluid, such as a dilute solution of protein used as a simulated tear fluid, may yield misleading liquid holding characteristics of surfaces due to preferential adsorption of components on a surface. 

In sessile droplet contact angle measurement, the advancing contact angle could be used to describe the surface characteristics, but the receding contact angle per se is a meaningless number unless its change with respect to the contact time can be utilized to analyze the surface dynamic nature of the surface. 

Weikart M. Christopher Miyama, Masayo Yasuda K. Hirotsugu. J. Colloid Interface Sci. 1999, 211, 28. 

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