Paint colour for backing plates ?

Well I hate oxidation so everything gets a splash of something. I'm in it for the long haul. I hate rust! I have 2 sets of backing plates, both painted so I am hoping not to have to buy more. Cheers!
Of course again just yesterday I was scrubbing the those clean and that's why I just threw my comment here out on the Forum. And I figured after 45 years there's absolutely not one wisp of rust or oxidation underneath all the brake dust. And you can see here in the picture where I just was like I'm going to actually scrub this all down to the galvanized metal everywhere? And it's a quarter inch away from facing the rotor. I'm feeling like at this point cleaning it is better than it's ever been in 40 of its 45 years. If it lasts another 45 years I'll be long dead.
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Taker easy...