The Sheen layer can simulate the grazing coloration or rim lighting in fabrics like velvet. It can also simulate layers of dust. See the Universal MaterialThe representation of the surface or volume properties of an object. topic in this manual for more information.
Figure 1: Sheen layer parameters
Sheen - The Sheen layer's color.
Roughness - The Sheen layer's roughness. Higher values spread the sheen color to larger parts of the surface.
Affect Roughness - The percentage of roughness affecting subsequent layers' roughness.
Bump - Simulates a relief by using a Greyscale texture interpreted as a Height map for the layer.
Normal - Distorts Layer normals by using an RGB image.
Layer Opacity - Controls the Layer opacity with a Greyscale texture.