What is brake glazing? How do you prevent it?

DSDP Don wrote:
Both hard braking and light braking can cause glazing. Think of it this way. When you drive down a hill to fast and have to use your brakes excessively, you heat them to the point that they glaze from the heat. Typically, to repair this damage you would have to turn the drums/rotors and replace the shoes/pads. Something you want to stay away from doing by using your engine/exhaust brake.

When you use them lightly, you're really polishing the drum/rotors and shoes/pads. Typically, a few hard stops will remove this type of glazing and get rid of the squealing that's usually associated with it.

This is why it's recommended not to use your engine/exhaust brake to extremes. In traffic and around town, exercise the brakes by using them. You're not going to wear them out.

I think you are confusing polished rotors with brake glazing. They are not the same thing. As far as I know, there is nothing wrong with shiny polished rotors. Is there?

Glazing means you melted the resins in the brake pads and they have turned into a glass like substance that doesn't have much friction. Most of that glazing will be on the brake pads, but you are correct that it could end up on the disc / drum as well and might have to be turned to remove the glazing. But glazed brakes look very different than smooth polished rotors or drums. (it looks like shiny spots on the brakes and they could look cracked). Polished = good, glazed = bad.

And if you drive down a hill too fast, yes, you will overheat the brakes whether you do it slowly or quickly, probably doesn't make a difference assuming you are driving too fast to begin with. That's exactly why you should use the engine brake -- to prevent this situation.