In the 1930’s, Vacheron Constantin looked to other industries in order to find other ways to varnish or paint their watches dial. E.I du Pont de Nemours and Company – later shorten to DuPont Company – was founded in 1802 by Éleuthère Irénée du Pont de Nemours (1771-1834) a French-American chemist and industrialist. His descendants were one of the richest families of the 19th century, with generations of influential businessmen, politicians and philanthropists. Initially manufacturing gunpowder, the company expanded its business, between 1902 and 1940, into chemical researches. Some of their discoveries led to painting, especially for the car industries in the 1930’s. And that is how Vacheron Constantin and DuPont Company met. The DuPont Company’s automotive lacquer product line was nicknamed Duco. These paint lacquers contain the material nitrocellulose which dried quickly giving an lacquer-enamel finish. That is the reason why, the watch manufacture used the Duco painting to coat some of its black dial with, between the 1930s and 1950s, to have the shiniest surface possible. These dials are extremely rare, specifically with the radium indexes.