Cycles, Materials Baked to Texture Lost Shading I'm very new to Blender, so this is probably a quick fix that I'm not noticing.  But, after having spent 2 days researching how I could fix this and coming up empty, I felt I should ask for help.

I've been trying to teach myself materials and node use through tutorials, and I just tried baking the materials to a texture.  I'm using Voronoi nodes to give polished detail to the steel part of the model, as seen in this picture.


But, when I bake the image to texture, I only get the gray base without the polished streaks from the Voronoi node.



Here is the node setup for the steel material.



And it was baked as Diffuse with only the color attribute selected.



If any more information is needed I'll gladly provide it.  Something inside is nagging me saying that this is a very simple fix that I'm just not noticing it.

EDIT 1:  I've added my Blender file.  

EDIT 2 - SOLUTION: Thanks to Carlo I was able to figure out what was going wrong and play around until I fixed it.  The problem I had was I was feeding the Voronoi node into a Bump feeding into the Diffuse normal, instead of feeding it in with the color.  I knew it was something silly simple I was doing wrong.  Also, like he mentioned, the Lighten node was destroying it too.  First thing first, I got rid of the Bump, and I put in a multiply mix, then set the contrast to low.  I got an effect that I'm actually liking better than the original because the polish streaks aren't so pronounced, but just barely noticeable.  Compare this material setup picture with the original and you'll see where I altered the nodes.





Thanks so much Blender.se community.  I really needed this.  And, I'm sure I'll be back again in the future as I continue my Blender learning adventure.  Have a great day!
"Lighten" mode needs brighter color in order to show something

With your setup are baking the Color component of the Diffuse pass. This means that the bake texture will show only the exact color input that's being provided to every diffuse shader in the nodes of your scene; no bump map/normals are being considered in this process, so the only way your texture could show some variations comes from the Mix factor of the Color Mix node (in your case set to Lighten blending mode)

Regardless of what color texture is coming into the factor, the output of the node will always be the light grey you see in the baked texture you are showing in your question: you are infact trying to Lighten a bright color with a darker one.



The manual is not quite clear about what the blending mode is doing:


  Like bleach makes your whites whiter. Use with a mask to lighten up a little.


I may guess is adding the second color only when it's brighter than the first one, but it's a fact that using a second color darker than the first one results in a color that is always the same of the first one.