My name is Owen Falk and I am a 4th year chemical engineering student at Stanford University. This summer I have been working on a research project that combines two of my great passions: cars and chemistry. At the onset, my project seemed simple: research a corroding race car from the 1950’s and find out as much as possible about the chemical reactions taking place. However, by the end of the first week it was clear that this project was much bigger than I expected.
The particular race car that I’m working on is the Cunningham C-4RK. This one-of-a-kind aluminum-bodied race car was built in 1952 by the great American sportsman Briggs Cunningham. The C-4RK was built with one purpose: to be the first American-built sports car to win the 24-hour race at Le Mans. With a body style foreshadowing Carole Shelby’s legendary Cobras and even the AC Ace designs upon which they were based, the C-4RK put on a great performance at Le Mans in 1953, leading the pack at the beginning of the race and setting a record for fastest lap. Unfortunately, the C-4RK crashed into a sandbank and ended up finishing 10th overall. After Le Mans, the C-4RK had a brief racing career in America before it was retired in the late 1950s and reacquired by Briggs Cunningham as part of his personal auto museum. Currently the C-4RK is owned by the Collier Collection and housed at the Revs Institute in Naples, Florida.
The problem plaguing the C-4RK is that its lacquer finish has become brittle and moisture is penetrating to the aluminum body beneath the lacquer, causing the car to slowly corrode. Even though the C-4RK is housed in a controlled environment with an expert maintenance staff to care for it, the corrosion persists. The good news is that the body of the C-4RK is comprised of a particular grade of aluminum that corrodes at an exponentially decreasing rate, meaning that the C-4RK would take literally thousands of years to corrode to dust.
To help explain what is occurring underneath the lacquer skin of the C-4RK please consult the figure above. The aluminum molecules in the body of the C-4RK are slowly converted to aluminum oxide in a process known as filiform corrosion. First the aluminum reacts with the salts present in the moisture solution, causing it to dissolve. Then, the aluminum reacts with oxygen molecules that seep in through the crack to form a milky white product that causes further damage to the brittle lacquer layer. It is important to note that without oxygen the corrosion reaction cannot continue. This suggests that a sealant could be used to prevent further corrosion.
The discovery that simply sealing the car could stop the corrosion was incredibly exciting, but it turns out that lacquer is exceptionally difficult to seal. I will extrapolate about this topic and others regarding the preservation of lacquer race cars in my future blogs.End