I painted the hub bit of my rear discs with silver Hammerite (standard Hammerite) when I replaced them, and they still look good now 4 years later.
So, when I replaced the front discs I did the same, but after 4 laps of the Nurburgring Nordschleife the paint was blistered.
From memory standard Hammerite is good for up to 120c but Hammerite barbeque paint is good for up to 600c.
I've bought one of those caliper paint kits in silver for the calipers which contains VHT paint, so if there is enough paint left over I'll sand down the front discs and redo them.
As a side note, I'm not trying to show off my single pot standard calipers, I just don't like the way they look when they go rusty!