How do I make a Decal look worn? I have what seems like a simple example here.  I wanted to practice texture and lighting by making some simple M&amp;M renders.  I used a NOISE texture for the surface to give it some "eggshell" quality in the render, I am progressing nicely.  Now I'm stuck...

I created the "M" logo as a PNG with alpha channel.  I applied it in the material using the image texture with mapping node and texture coordinates.  All basic stuff so far.

I can't for the life of me figure out how to use procedural nodes like Voronoi or Noise to make the stark white of the M Logo look "worn" so some of the color of the M&amp;M show through, like it's scuffed.  Now the render isn't convincing because every M is too perfect.  I know I could use my image editing software to make some alpha transparencies in the PNG decal, but then they would be the same across all meshes, and I was hoping to use a NOISE node to randomize it a bit.

Can't I use a NOISE tesxture to a COLOR RAMP then make one of the colors ALPHA transparent thus having the M logo "Fade" and let the color show through?  I think I've tried 100 different things and I am not getting it.  (I am not a Blender expert but have an intermediate understanding of texture node setups...)

Here's a link to my .blend file in my dropbox, without ANY treatment on the M logo.  You can see they are too stark white and perfect.  I want to scuff just the logo up.  Any ideas?  Thanks in advance!  (Render is formatted for dual monitors so please ignore the odd render dimensions!)

Blend File in Dropbox
Given that you are using the alpha channel as a mask to control the mix of different elements, you need to make the mask less perfect. Instead of being a perfect white mask, you need to subtract from the white using a texture. Why subtract? Think of white as 1 and Black as 0. You want to affect the mask without adding any more information to the black areas. 

 

Subtract a texture from the alpha channel, and use the result as a Mask to control the mix for the color for the shader.



Combining other textures and subtracting them from the alpha you can further distress a texture to seem more random.