Standard Shader (Metallic workflow)

Unity's default Standard Shader combines Albedo and Metallic/Glossiness maps to create the color and reflectance qualities of the material. The following are the differences:

• Albedo: As in the Specular workflow, this is the Material's diffuse color; how you would describe the Material. However, Albedo maps for the Metallic workflow should be configured in a slightly different way than ones for Specular workflow. This time around, the perceived diffuse color of metallic materials (grey for iron, yellow/orange for golden, and so on) have to be present in the Albedo map. Again, Albedo maps feature RGB channels for the colors and (optionally) an Alpha Channel for transparency.
• Metallic/Smoothness: This refers to how metallic the Material looks. Metallic Texture Maps make use of the Red channel for the Metallic value (black for non-metallic and white for metallic Materials that are not painted or rusted) and the Alpha Channel for smoothness (in a similar way to the Specular workflow). Please note that Metallic maps do not include any information on hue, and in these cases the yellow-ish nature of the metallic gloss should be applied to the Albedo map.

To reproduce the battery that illustrated the Specular workflow by using the Metallic workflow, maps would have to be recreated as follows:

You might have noticed that we've used white to convey a metallic object. Technically, since only the Red channel is relevant, we could have used red (R: 255, G: 0, B: 0), yellow (R: 255, G: 255, B: 0), or, for that matter, any color that has a red value of 255.

The Unity documentation pages provide two very useful charts giving examples of common properties for the Standard Shader Metallic and Specular workflows (https://docs.unity3d.com/Manual/StandardShaderMaterialCharts.html):