Apparently, the “bold vivid color” of El Marko watercolor markers, made by Flair, were not long lasting enough. The pens have disappeared, though Flair pens survive, made by Newell Rubbermaid’s Paper Mate division.
In 1955, Paper Mate became part of Gillette. The Flair was launched in 1966. Gillette’s Stationary Products Division became part of Newell Rubbermaid in 2000. No word on when El Marko disappeared.