The coating material simulates a thin coating of some kind of material over another material. For example, you can create a thin coating of varnish over a metal material.
The coating material can also simulate interference, which can give interesting effects when the thickness of the coating varies with position:
Depending on the thickness of the coating, and how the thickness varies over the object (which can be controlled by a shader) you may get a kind of rainbow effect, or the material may just take on just a few colours:
A coating can also absorb light, which will result in a tinted colour:
Coating material attributes
Controls the absorption of light as it travels through the coating layer.
Controls the thickness of the coating layer. In the Indigo graphical user interface, the thickness is given in units of micrometres (μm), or millionths of a metre.
A thicker layer will have stronger absorption.
If enabled, thin film interference is computed for the coating layer.
The result will be most noticable when the coating layer is on the order of 1 μm thick.