oilfilm

An oil film, sometimes written as oilfilm, refers to a thin layer of oil that rests on a different phase, typically water or a solid surface, due to immiscibility and differences in density and surface tension. Oil films form when oil spreads across a surface after a spill, leak, or as a product of lubrication and surface treatments. On water, an oil film can range from a few nanometers to several micrometers in thickness. The layer affects interfacial properties, decreasing surface tension at the air–oil or oil–water interface and altering wetting, roughness, and friction.

The optical appearance of an oil film is highly dependent on thickness, producing iridescent colors from thin-film interference. The film’s stability depends on viscosity, temperature, evaporation rate, and transport processes such as diffusion and advection. In many cases, the film is bounded by an underlying substrate and can be disrupted or removed by mechanical skimming, adsorption, emulsification, or chemical dispersants.

Detecting and measuring oil films uses aerial or satellite imaging, infrared or UV spectroscopy, ellipsometry, and interferometric techniques, as well as radar remote sensing for larger slicks. In engineering contexts, controlled oil films serve as lubricants to reduce wear and as protective barriers; improper films can cause fouling, slippery surfaces, or environmental harm.

Environmental considerations are significant: oil films can concentrate contaminants, affect marine organisms, and persist depending on oil type and weathering. Cleanup and containment strategies vary with thickness, location, and regulatory frameworks.