Looking for high-temp (for brakes - not exhaust or engine) rusty metal primers/paints - I can’t seem to find any.
Rust oleum makes rusty metal primer but I don’t think it is rated for any high T applications.
Maybe POR-15 has a high-T product but not sure. UPDATE : POR-20 is high-T, namely 1500 degrees F (see below)
and also I think POR stands for “paint over rust” but I could be wrong
How about a rust converter and then using High Temp paint over the neutralized rust.
Why not use exhaust temp. rated paint. I think the exhaust manifold gets hotter than calipers.
I use 1200 degree Rutland stove paint for projects like that. High temps don’t affect it at all.
Parts stores sell this.
As with any paint job, surface prep is critical.
Tester
The best way is to clean the rust off first, preferably with a sandblaster or wire wheel. The rust converters should work as a prep but I’m not sure how much heat it can take. The high temp caliper paint works great on bare metal so it should work well over the rust converter. Unless you are starting with rust-free metal, you will likely need to periodically touch up.
FWIW, I always paint new brake rotors with caliper paint on the hat section and the edges to keep them pretty under my wide-open wheels. I avoid putting much paint on the friction surface as the pads will just wipe it off.
some more reading turned up this : POR-20 is heat-resistant to 1500 degrees F. I think this covers braking systems.
also to emphasize : as I am interested in rusty-metal paints, I am NOT interested in sandblasting. In that case, I would electroplate. I have already had this done to my brake calipers by a professional company. If rust is there, then it is there for a reason - i.e. technical difficulty in removal (by them, anyways).
and also to emphasize - I am not interested in brake caliper paints because I think brake fluid will strip it off, also there is curing to be done for true effectiveness - which POR-20 seems to avoid for some reason.
my Sebro brake rotors for my 1987 Porsche 944 NA have what looks to be primer gray on the “hats”. Got me thinking that e.g. POR-20 would be better for this application.
Just a little 411 from personal experience, brake caliper paints are not stripped off by brake fluid, yes there is curing but it can use the heat generated by normal use or you can stick them in your grill for 20 minutes (for the OCD among us) let them cool and install.