Thin Film reproduces the effect of thin film interference on a surface. It can be used for materials, such as multitone car paint, burnt chrome or the reflective coating on a beetle (Thickness: 400, IOR: 1.43).
Rollover images to view without Thin Film
The following Standard Surface shader settings were used to create a soap bubble.
Specular Color: 1 1 1
Specular Roughness: 0
Specular IOR: 1.0
Transmission Color: 1 1 1
Coat IOR: 1.5
Thin Film: IOR 1.4
Thin Film Thickness: 500 [nm]
A grayscale map should be connected (through a Range shader) to Thin Film Thickness if variation in the Thin Film is required.
More Information about soap bubble color and film thickness can be found here.
How Thin Film is Modeled
How to Map IOR values from Thin Film to Standard Surface