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Add-on: Material Slots Cleaner (Free)


Nazzareno Giannelli writes:

Remove unused material slots from all selected meshes at once in Blender 2.81.

This simple addon is not deleting unused materials from your blend file, but instead is checking each selected mesh and removing unused material slots that could have been still attached to your meshes. I found it pretty useful in cases were you have to separate an imported fbx into different pieces. By default all the newly created meshes will inherit all the applied materials of the original fbx, even if the single mesh does not use all of them. With MatSlotCleaner, instead of having to go through each mesh and remove unused slots, you can do it with just one click.

About the Author

Nazzareno Giannelli

The beauty of interior design and architecture, the interactivity and flexibility of digital art. My job is to create interactive experiences grounded into reality, to bring content, tools and knowledge to other creatives allowing them to express themselves. After many years as a 3D artist I am now shifting toward more technical skills like scripting and pipeline optimization. I love bringing visuals, interaction and sounds all together for a fulfilling experience, taking the users to new places, letting them explore.


  1. Awesome idea. I've been running into this problem lately. Now if someone would come up with a way to remove unused Vertex Groups as well I'd be in business, hint, hint.

    Thanks for this though. Can't wait to try it out.

    • Thanks for checking it out :)
      I could try to look into the vertex color thing. It shouldn't be so much different to solve.
      I am personally using them just for ID map in Substance Painter so...I never run into that issue.

  2. I import a lot of Daz and Poser content which tend to have lots of vertex groups. When separating I run into the same issue as with the material slots. Don't know if others have these issues.


  3. Fantastic add-on! Saves a lot of time.

    I have a big problem with a slightly different issue. I have a library that I use for most of my projects, and I append many assets. I therefore end up with many duplicate materials like for example Glass.001, Glass.002, Glass.003, White.001 and White.002, and they are identical materials that are all used in an object. Could it be possible to merge all these materials that are identical into one name? Or do I need to change my workflow somehow..?

    Best regards

    • I've tried it.
      Some materials are not removed...
      I've imported a Daz figure and running Blender 2.91.0 and most of objects keep 2 or 3 unused materials.
      Every material have been formerly removed from the Outliner > Blender File.

      I've made a material copy with ctrl+l, perhaps it caused this issue?

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