Can the Principled BSDF shader be used with a specular workflow?

It is my understanding that the Principled BSDF shader is basically for the PBR Metallic workflow. Am I correct in thinking it can’t be used for the specular workflow?

On that subject, is the metallic workflow becoming the default over specular? Doesn’t it contain less information? For example, the metallic workflow contains no diffuse information for metals and no specular information for diffuse. Do those just play so little role that they aren’t needed?

you can get some diffuse equivalent by increasing the roughness value!

and PBR is all Specular that is the idea behind it !

happy cl

Actually, a PBR shader is not just specular. There’s also diffuse, SSS, transmission, refracting, and retro-reflection/velvet components as well.

What PBR has is real specular (as opposed to the fake effect in legacy render engines), that is where the highlights exist because the material itself has at least some level of reflection (at varying roughness values). The Metallic component is supposed to allow for the render of metals (you generally want it at a value of 0 or 1, but you can go anywhere in between for artistic reasons).

There are two main workflows for describing a material for PBR. The Unity Manual has good documentation on this ( but put simply:

Specular Workflow

Albedo: Describes the diffuse reflectivity of the material. For dielectrics this is the perceived color of the object. For metallics this is black or near black.

Specular: Describes the specular reflectivity of the material. For dielectrics this is always a dark grey, and for metallics this is the perceived color.

Smoothness: Describes the perceived glossiness/roughness of the material

Metallic Workflow
Albedo: Describes the overall color of the material for both dielectrics and metallics.

Metallness: Describes whether or not the material behaves like a metallic, i.e. has colorful specular reflections (metallic) or white.

Smoothness: Describes the perceived glossiness/roughness of the material

These are different methods of describing the same materials, and they have slight advantages and disadvantages. To my knowledge, the Principled BSDF shader uses the metallic workflow. I am wondering if there is a way to use the Specular Workflow in Blender.