ASTM D1331 Surface and Interfacial Tension of Solutions of Surface Active Agents
For oil to protect a metal, it must first “wet” or coat the metal. Surface tension gives an indication of oil’s metal-wetting ability. In general, the lower the surface tension of an oil, the greater its wetting ability. This test determines the surface tension of oils.
The force that separates oil and water into two layers is interfacial tension. Interfacial tension may indicate how well oil will displace water to coat moist metal. Decreases in interfacial tension of service oil may indicate contamination or oxidation.
Both surface tension and interfacial tension are measured using a du Nouy Tensiometer which has a platinum ring attached to a calibrated force mechanism. The ring is placed slightly below the surface of the oil (surface tension) or water (interfacial tension). The force on the ring is gradually increased until it breaks through the surface of the oil or water. The measured force and the sample density are used to calculate the surface or interfacial tension. The values are reported in dyne-cm. Please specify the desired temperature.
Instructions:
Needs Temperature: 20°C or 25°C