This tutorial demonstrates a workflow for blending localized dirt and grime into 3D assets using masks driven by a secondary UV pack. It is particularly useful when working with trim sheets, allowing you to add unique wear details without requiring entirely unique textures, or to unify multiple environment assets with shared dirt materials.

The guide covers setting up a basic master material in Unreal Engine 4, creating a secondary UV pack in Blender, and generating channel-packed masks in Substance Painter. A sample barricade bus asset and the necessary textures are included so you can practice the workflow directly.