Coat Amount – Specifies the blending weight of the coat layer. A value of 0 does not add a coat layer, while higher values blend the coat gradually. See the Coat Amount example below.

Coat Color – Determines the coat layer's color. A texture map can be used here.

Coat Glossiness – Available when the Surface Control option is set to Use Glossiness. Controls the sharpness of reflection. A value of 1.0 means perfect glass-like reflection; lower values produce blurry or glossy reflections. See the Coat Glossiness example below.

Coat Roughness – Available when the Surface Control option is set to Use Roughness. Controls the sharpness of reflection. A value of 0.0 means perfect glass-like reflection; higher values produce blurry or glossy reflections.

Coat IOR – Specifies the Index of Refraction for the coat layer.

Available only in Advanced mode.

Mode / Map – Allows the user to specify whether a bump map or a normal map effect is added to the base material.

Bump Map – Requires a height map.

Bump Texture Channel – Most commonly used for the Round Edges effect (Edges texture used as bump).

Normal Map – Requires an RGB map. If a Bitmap texture is slotted, its color space must be set to Rendering Space (Linear).

Amount – Multiplies the Bump / Normal effect.

Example: Coat Amount

This example shows how Coat Amount affects the look of the material. The base Reflection Glossiness is set to 0.76 and the Coat Glossiness is set to 1. The value of the Coat IOR is set to 2 and the Coat Color is the default white.

Example: Coat Glossiness

This examples shows how Coat Glossiness controls the sharpness of the coat reflection. Here, the base Reflection Glossiness is set to 0.76 and the Coat Amount is set to 1. Coat IOR is 2 and the Coat Color is the default white.
Notice how higher values produce glossier reflection and lower values make it look blurry.