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1. It provides a richer specular response to light as it adds a specular highlight on top of the base surface's highlight.
2. It can colour light as it passes through the coating.
3. It contains metallic particles (a.k.a flakes) suspended inside the coat. 

 
Thickness

The thickness of the coating layer. The thicker the layer the more it absorbs light and the less of the base layer is visible. A thickness of 0 disables the coating 

Specular Level

coating.

Image AddedHow "shiny" is the coating. A value of 1 means a very shiny coating.

Color

The colouring producing by this coating layer. Colouring will be more prominent in thicker layers.

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Roughness

Roughness of the coating layer.

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Specular Level

How "shiny" is the coating. A value of 1 means a very shiny coating.

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Color

The colour of the base layer.

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Weight

Color

Scale

IOR

Anisotropy

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Merge Set

When two or more subsurface volumes overlap, their internal boundaries can create darker (or brighter) areas on the surface. Setting their Merge Set to an identical name disables those boundaries and their effect on the surface, effectively merging the volumes together.

Dominant Material

When two or more subsurface volumes overlap, a mix of their properties will normally be used inside their intersection. Checking this option for one of the materials will prevent this mixing and ensure it's used exclusively.

Double-Sided

Allows the SSS simulation to be entered and exited from the front or the back of a surface. When this option is disabled (the default), the simulation is entered only from the front and exited only from the back.Image Removed

Color

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Colour of the emitted light.

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Intensity

Intensity of emitted light. Final colour is Colour * Intensity.

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