Many vehicle owners using disc brakes often notice that the wheel rims turn black. Most of these black marks come from "brake dust," which mainly originates from the wear particles generated during friction between the brake pads and the disc. This article provides a complete analysis of why brake dust forms, which materials are most likely to cause it, whether it affects safety, and how to reduce rim blackening.
Why do brake pads make wheel rims turn black?
The main components of brake pads include resin, rubber powder, graphite, and metallic fibers. Under high-temperature friction, organic materials undergo thermal decomposition and carbonization, producing fine black dust. Metallic fibers wear down during use and react with oxygen to form metal oxides, which are typically gray-black or dark brown. These fine particles are very small, often sticky on the surface, and easily adhere to the rim. In humid environments, brake dust combines with moisture, becoming more viscous and harder to clean.
Which materials most easily produce black dust?
For semi-metallic brake pads, the main contributors are iron powder, steel fibers, and graphite. For organic brake pads, the main source is organic material that carbonizes after exposure to high temperatures.
Do brake rotors also generate black dust?
Yes. Brake rotors are usually made of iron-based material. Under friction and high temperature, they oxidize to form FeO, Fe₂O₃, and Fe₃O₄. The standalone amount is not large, but when mixed with carbon dust from brake pads, adhesion increases significantly, making the black marks on the rim more visible.
Does black dust affect braking performance?
Most black dust only affects appearance and does not directly compromise braking performance. However, if left uncleaned for a long time, dust can accumulate between the brake pads and the disc, which may increase the likelihood of noise.
How to reduce black marks caused by brake pad dust
To reduce rim blackening, choose low-dust brake pads such as ceramic pads or low-metallic formulas. During friction, they produce larger and lighter-colored particles, which are less likely to adhere to the rim.
Does using ceramic brake pads mean there is very little dust?
Not exactly. The amount of dust is not necessarily reduced, but the dust tends to be lighter in color—white or gray—so it looks less noticeable. In addition, durability and the aggressiveness of the pad toward the rotor can also influence how much dust is generated.
Is black dust easy to clean?
If you choose ADUI products, we offer two grades of ceramic pads. The first grade has long lifespan and low wear, resulting in less dust, with almost no visible black residue. The second grade has medium lifespan and medium wear, but stronger braking force. Although it produces more dust, most of it comes from organic material, which does not easily stick to the rim.
Is stronger braking force always equal to more dust?
Not necessarily. Braking force depends on the friction coefficient, while dust production depends on the wear rate. Some high-friction formulations are reinforced for durability, allowing both strong braking force and low dust. However, the cost of such formulations is usually higher.
Which formulations are suitable for users who want clean wheel rims?
Ceramic brake pads and low-metallic brake pads are usually the best choices. They generate less dust and the particles are lighter in color. Combined with regular cleaning, they can effectively keep rims clean.
ADUI is a specialized brake pads manufacturer. We offer brake pads in a variety of materials and can adjust performance and lifespan according to customer needs, providing products that best meet client requirements.
