Rendering the Enforcer - ZBrush Creature Design: Creating Dynamic Concept Imagery for Film and Games - page 659

8. Use the Save As button in the Material palette and save the material as SpecularShader.ZMT.
9. Save the project.
Create the Subsurface Scattering Shader
The last ingredient for the skin shader is the subsurface scattering. This is what helps bring the skin to life by
adding that luminescent quality. Working with subsurface scattering (SSS) in ZBrush is a little tricky since
there are a few ways to create this effect and the interface is not terribly intuitive. The goal is to add a hint
of reddish color that is stronger on the thinner parts of the model. If the effect is too strong, the model will
look like wax or plastic.
It is best to develop the SSS shader in isolation so that the influence of other material properties, such as
the diffuse and specular highlights, doesn't confuse the result.