Rusted material

This is a rust shader I created recently. It has a few areas that could have used more focus when I was painting, but I was more focused on getting the material to look correct. I will likely return later to this and correct the painting, but it is already functional and can be implemented by appending into another file and painting a Black and white rust map.
I’d love any notes about how to improve it.

Software: Blender 2.78.5
Hardware: Intel core 17, Nvidia Geforce GTX

Resources and References used