The Sheen tab is part of the V-Ray Mtl parameters.
Input Sockets
This section describes properties that are found only on the node itself.
Sheen Amount – Specifies how much the sheen layer overlays the diffuse color. The higher the amount, the more of the sheen color you get. An integer-outputting node can controls this parameter, or the value can be set manually. See the example.
Sheen
A Sheen layer can be used to create cloth materials such as satin.
Sheen Color – Specifies the color.
Sheen Glossiness – Controls the sharpness of reflections. A value of 1.0 means all of the light reaches the diffuse color, and when the value is smaller, the cloth material looks glossier. See the example.
Example: Sheen Amount
This example shows how changing the amount of the sheen layer affects the material. Glossiness is set to its default value.
Example: Sheen Glossiness
This example shows how changing the glossiness parameter of the sheen layer affects the material. The Sheen Amount is set to its default value.