The boiling point of brake fluid is the temperature at which the fluid begins to change into a gas. This value is given in degrees Celsius and describes the thermal resistance of the fluid during intensive braking, when the brakes heat up significantly. If the temperature in the brake system exceeds the boiling point, vapor bubbles form in the fluid. Unlike fluid, vapor is compressible, which leads to the brake pedal sinking and a significant reduction in braking efficiency. This phenomenon is called „vapor lock“. A boiling point value of 260 °C is typical for the so-called „dry boiling point“. This is the boiling point of fresh fluid from a newly opened package that has not yet absorbed any atmospheric moisture. Brake fluid is hygroscopic, which means it absorbs water over time, thus lowering its boiling point.