I’m having trouble getting my texture painting to show in my final render, but I don’t know what I’m doing wrong! I’ve unwrapped the uv, created a new brush, but for some reason it still doen’t work!
This is how I tried to create my texture brush (Skip to 11:15)
This is my screen in texture paint mode.
But then this is the render.
Any help is greatly appreciated. 
Is your material set up correctly? White area could be some object you only hide for viewport but is shown in render and the red object is behind it?
After painting, make sure you save the material and then make sure you’ve updated it in the node editor.
Actually, the red part is a trim around the white object! 
Thank you! That seemed to work after saving the updated image.
As a follow up question, do you know an easy and simple method to change the material of ONLY the black area? Say, If I wanted it to still be the same color, but not shiny, as if the shine was rubbed off on that part of the metal.
You’d have to set the black part as a mask, I assume, but I’m far from an expert on node setups. I put this together a couple of years ago… I can’t recall the original author, but I got the content from the Blender Stack Exchange, so I hope the creator doesn’t mind if I post it here.
Edges_Weathering_tutorial.pdf (2.2 MB)
I’m not an expert so I’ll look up some mask tutorials. Btw, I also encountered this problem…