The pendant drop/bubble method is widely used to measure the surface tension for various shapes of liquid drops or air bubbles. It was found previously (Langmuir 11, 4159, 1995) that the surface tension is bubble (drop)-size dependent. In this study, the effects of the aspect ratio (a(r)) and the horizontal dimension of a pixel (l(x)) on calculation of the surface tension were systematically examined. A two-step procedure for tuning a(r) and l(x) is proposed to eliminate the bubble (drop)-size dependence of the surface tension. Four liquids, water, ethylene glycol, n-hexadecane, and n-octane, were used to test this procedure. and excellent results were obtained. Essentially, the bubble (drop)-size dependence of the surface tension vanishes after the two-step tuning procedure is applied. [References: 13]
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