Only part of texture paint is pink I have an object that has been created by joining two objects. The entire thing has been uv mapped. When I go to "texture paint" the entire model is pink, which I expect. I click "Add Texture Paint Slot" and add a blank texture, which renders a large part of the model black (and paintable). However, all of the faces of the second object (and by "second" here, I am referring to the order of the objects when they were joined) are pink. I can paint directly on the part of the texture that is black, but I can't paint on the pink part. 

Any guidance or suggestions would be appreciated!
Select all faces and assign them to the same material. It is likely that your two objects had different materials on them, and that you added the texture paint slot to your first object's material. Now that all the geometry is in the same object, what previously was the second object is still using its material, which didn't get the texture.