Brake dust is a common issue for car owners, often visible on wheels and other parts of a vehicle after driving. While it may seem like an aesthetic nuisance, brake dust is a normal by-product of the braking process.
In this article, Scott Irwin, Head of Technical Training at Textar, explains what brake dust is, where it comes from, and whether it affects braking performance.
What is brake dust?
Brake dust consists of tiny particles created during the braking process. It may appear as dark or rust-coloured build-up on your vehicle’s wheels and rims. Brake dust is a perfectly normal by-product of the friction produced during the braking process and is not generally a cause for concern.
Where does brake dust come from?
Brake dust is an inevitable by-product of friction, which arises when slowing or stopping a moving vehicle. The amount and type of brake dust generated during the braking process is part of the complex physiochemical processes between the brake pad and brake disc in order to achieve the desired braking characteristics. It can vary depending on several factors such as the brake pad composition, driving habits and environmental conditions.
The material used in the brake pads plays a significant role in the amount and type of brake dust produced. There are three primary types of brake pad materials – low steel, semi-metallic and non-asbestos organic (NAO). The material chosen depends on the vehicle application and the required properties, and is tailored to perfectly match the braking system and environment it will be used in.
Whilst the brake pad is responsible for some of the dust created during the braking process, around 80 per cent of the emissions or dust is abrasion from the disc. The amount of disc material removed depends on the selected friction material formulation of the brake pad.
The materials are not entirely to blame for brake dust creation – driving style has some part to play too. Aggressive driving, such as hard braking or frequent high-speed deceleration produces more friction, which in turn generates more brake dust. Stop-and-go city driving also leads to greater dust accumulation compared to long-distance highway driving, where brakes are applied less frequently.
In addition, external factors like road grime, rain, and the type of roads driven on (e.g. dusty or salty roads) can interact with the brake system, contributing to or influencing the development of brake dust. Vehicles used for high-performance driving or off-roading often experience more rapid dust accumulation due to the more intense use of the brakes.
Does brake dust affect performance?
Brake dust itself does not directly affect braking performance. The dust is a by-product of the friction needed between pads and discs to slow or stop the vehicle, but as long as the brake components are in good condition, the dust will not impact the vehicle’s ability to brake effectively.
However, brake dust may have an indirect impact on braking performance if it accumulates on other brake system components such as the caliper. With excessive dust build-up, the caliper may not be able to move as freely, reducing brake performance. When performing a brake replacement, technicians should therefore remove dust from the caliper and other braking system components.
There are several wheel cleaners available to easily remove brake dust from the wheel, however, some of these can be very acidic and harsh to certain surfaces and coated discs, as well as affecting the rubbers used in the brake system. Textar always recommends reading the manufacturer’s instructions and testing a small area first. In addition, when working with chemical cleaners or airborne particles, Textar recommends wearing a mask.
Environmental impact of brake dust
Brake dust is not just an aesthetic nuisance – it can also have a negative impact on human health and the surrounding environment. In 2024, new Euro 7 standards came into effect, putting brake emissions into focus for the first time. For those manufacturers selling into the EU, the new legislation will limit the abrasion of brakes in the future.
TMD Friction, the parent company behind Textar, is currently working on low emission brake concepts to comply with the new Euro 7 emission standard. This means less brake dust in the air – and on your rims.
Final thoughts
Brake dust is an inevitable by-product of the braking process, resulting from the friction between the brake pads and discs. While it may be an aesthetic nuisance, it does not affect braking performance. The amount of brake dust generated depends on factors such as the type of brake pad material, driving habits, and the design of the braking system.
To remove brake dust, regular cleaning with a reputable and suitable product is recommended. Additionally, choosing the appropriate type of brake pads for your driving style and conditions can help minimise dust build-up, extend the life of your braking components, and maintain optimal braking performance.