Title: symmetrical films
Long Title: IUPAC Gold Book - symmetrical films
DOI: 10.1351/goldbook.S06211
Status: current

Definition
The properties of fluid films depend on the nature of the film phase and that of each of the two neighbouring bulk phases. These films should be described, where appropriate, by three capital letters such as A for air, W for water, O for oil, and S for solid, separated by solidi, the middle letter indicating the film phase. For symmetrical films the first and last symbols are the same, e.g. A/W/A: water film in air, or W/O/W: oil film in water, whereas for unsymmetrical films these are different, e.g. W/O/A: oil film between water and air.

Related Terms
- asymmetric film: https://goldbook.iupac.org//terms/view/A00482
- film: https://goldbook.iupac.org//terms/view/F02366

Source
- PAC, 1972, 31, 577. 'Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry' on page 613 (https://doi.org/10.1351/pac197231040577)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/S06211/html
- json: https://goldbook.iupac.org/terms/view/S06211/json
- xml: https://goldbook.iupac.org/terms/view/S06211/xml

Citation: Citation: 'symmetrical films' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.S06211
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Accessed: 2026-04-27T18:04:48+00:00