Bedding & Burnishing

The Science

Brake “bedding”, as it’s commonly referred to in the U.S., actually involves two distinct processes - bedding and burnishing.

Bedding is the first of these two processes. 

New pads and rotors have rough surface textures and initially have minimal surface area contact and the goal of bedding is to maximize the contact before moving to the second process. Increasing surface area contact occurs when the pad, the softer of the two friction materials, conforms in shape to the rotor, the harder of the two friction materials. During this process, pad material is transferred to the rotor surface and the topography of the mating surfaces begin to match.

*Note: The amount of surface contact is known as “percentage bedding” and any unworn surface area on the rotor is proportional to its percentage below 100% “bedded”. The lower the percentage bedding before initiating the burnishing process, the more likely the chance of brake noise and/or sub-optimal brake power.

Burnishing is the second process.

Burnishing is the act of sliding friction materials against one another to create a tribofilm, or “transfer film”. The friction surfaces, when subjected to enough pressure, undergo a mechanical, thermal and chemical transition. The resulting film deposit is composed of binder resins, friction modifiers, metallic particles and environmental debris and results in a change of friction surface topography and metallurgy. Basically, the tribofilm makes the braking surfaces stickier, and once formed, act as a boundary layer between the components prolonging their service life.