How to import Poliigon surface imperfection maps in Blender
The easiest way to import Poliigon imperfection maps into Blender is by using the Poliigon Blender Addon, located here: https://www.poliigon.com/blender
Once you've imported the map to your scene, you'll notice that the addon imports it as a distinct material, which isn't what we want
Select the material in the Materials section of the Properties panel, then in the Shader Editor workspace, drag to select the nodes prior to the Principled BSDF node, and copy them
Note that some assets may have two variations of the roughness/gloss map. You want to select the map that has white details on a black background. You can preview a node in the viewport by pressing Ctrl+Shift+Left Click on the image texture node, assuming you have the Node Wrangler addon installed, which ships with Blender)
Note that some assets may have two variations of the bump map. Which map to select will depend on the intended use, but for maps intended to make indentations (for example, scratches), select the map with black details on a white background.
Select the material you want to add the imperfections to and paste them into the Shader Editor workspace. We'd recommend leave both sets of mapping nodes, as you may find that you want to adjust the scaling of the imperfection map independently of the material itself
To import an imperfection map manually, add an image texture node through the Shift+A menu while in the materials Shader Editor workspace, then click the folder icon to manually browse to the map file you downloaded. You'll need to make sure you set the Color Space properly for the type of map imported. E.G. Diffuse map should use sRGB, Roughness should use Non-Color etc.
How to set up Poliigon surface imperfection maps in Blender
For Basecolor/Diffuse maps:
use the Shift+A menu to add a Mix Color node, and place it between the Basecolor/Diffuse map, and the Principled BSDF.
Connect the Basecolor node to the top input, and the imperfection node to the bottom.
Set the mix type to "Screen" then adjust the Fac slider to the desired strength
For Roughness maps:
use the Shift+A menu to add a Mix Color node, and place it between the Roughness map, and the Principled BSDF. If you're working with one of our older materials that has a gloss map, place the node after the Invert node
Connect the Roughness node to the top input, and the imperfection node to the bottom.
Set the mix type to "Screen" then adjust the Fac slider to the desired strength
For further control over the look of either of the above maps, you can add a Color Ramp node between the imperfection map and the Mix Color node, and adjust the positions to the desired look
For Bump maps:
use the Shift+A menu to add a Bump node, and place it between the Normal Map node and the Principled BSDF
Connect the Bump map to the "Height" input.
Adjust the "Strength" and "Distance" to achieve the desired look
