Take your time and make sure the calipers are clean. Use the brake cleaner, sandpaper, towels, brush, whatever it takes to get any crud off them. Mine were pretty clean but I used a small brush to help. Once that dries tape everything off that is touching parts you are going to paint. I put 4...
This worked for me to get the nut, but the washer is still evading me.
https://www.amazon.com/gp/product/B008Z67LU8/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
I have used it several times on mine with no issues. Spray it on, let it sit for a few, then blast it off with the pressure washer. I stopped using it as my wheels haven't been getting as dirty and caked with the brake dust since coating them.