Hiya peeps!
There may be differant ways of powder coating, but as far as i am aware the powder is sprayed on then the object is baked at a high temperature to cure the paint. This si how things udes to be powder coated where i used to work. Obviously, if u intend to do this with Calipers they must be stripped down and sprayed, then re assembled, otherwise the heat from the baking will destroy all of the seals in the Caliper. Like i said, there might be other ways of Powder coating, but this is the process I am familliar with. Hope this helps,
Regards, tony.