Dark/light bands on brake discs

[techathy]

No so much a problem but I've noticed that my brake discs keep on getting dark & right rings on. The rings change location on any drive with hard braking & sometimes disappear on sedate drives with lots of light braking.

I've never had this before on a car, but I've also never had so much brake dust produced by a pad as these. Should I be worried or is it just side effect of dusty pads?

 

[SO8]

Pads and the temperature reached I guess relative to the material and the metal disc ... I have only seen blue discs on a car - and was told I was driving it / braking too hard and overheating the discs ... oops ... well it was a police traffic car :evil:

 

[Beedub]

it's just pad transfer when they get hot, thats normal