Brake Pad History
Asbestos Brake Pads
When disc brakes first appeared on production cars in the 1950s, asbestos was used in brake pads. Asbestos brake pads were popular because they dealt with high heat very well and the health effects of asbestos weren't known.
Organic Brake Pads
Organic brake pads replaced asbestos pads once the affects of asbestos were learned. Organic pads use carbon instead of asbestos. Organic brake pads don't provide very good resistance to fade, so they were replaced with semi-metallic pads.
Semi-metallic Brake Pads:
Most brake pads sold today are semi-metallic. Semi-metallic brake pads usually use chopped steel wool mixed with resin. It's easy to tell the quality of a semi-metallic brake pad: smooth is good. The more finely the metal is chopped in a semi-metallic brake pad, the better the pad will be at dispersing heat and resisting fade. A cheap semi-metallic brake pad will be rough to the touch and could even leave metal splinters in your hand. A good quality semi-metallic brake pad will be smooth to the touch.
Ceramic Brake Pads:
Ceramic pads have replaced semi-metallic brake pads in many applications. First used on production cars in the mid 1980s, ceramic brake pads use copper instead of steel to conduct heat away from the rotor. Ceramic brake pads provide better stopping power and less brake fade than semi-metallic pads. The brake dust from ceramic pads is light colored and doesn't stick to wheels, which means you won't get any of that black dust covering your wheels.