SYMPOSIA PAPER Published: 01 January 1984

The Drop-Weight Interfacial Tension Method for Predicting Dispersant Performance


The drop-weight test is an improved interfacial tension method for predicting the relative effectiveness of oil-spill dispersant products. The test is based on the relationship between the weight of a drop of oil detached from a capillary beneath a dispersant-in-seawater solution and the lowering of the interfacial tension between oil and water. A modified test procedure, based on measuring the time for a drop detachment rather than the weight, significantly reduces the test time and simplifies the apparatus. Another modification permits the determination of relative diffusion rates of dispersants through an oil column. Seventeen water-based dispersant products were evaluated with light Arabian crude oil and, in some cases, with No. 6 fuel oil using the modified procedures. The results were interpreted in terms of data reliability and compared with information obtained by a standard test.

Author Information

Rewick, RT
Sabo, KA
Smith, JH
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Developed by Committee: F20
Pages: 94–107
DOI: 10.1520/STP30231S
ISBN-EB: 978-0-8031-4906-9
ISBN-13: 978-0-8031-0400-6