Test strips are available that employ copper-testing technology, and they are used as an indicator of corrosion occurring in the brake system. Most brake tubing is manufactured using the Bundy process. This process uses copper-coated low-carbon steel to form double-wall tubing with protective coatings that prevent corrosion to the outer surface of the tube. Andrew Markel shows why regularly testing brake fluid is necessary due to the construction of Bundy tubing.