Copper (#B87333) and Dark red (#8B0000) appear together across 6 master palettes in our corpus, most prominently in the work of Matthew Smith, Erik Wahlberg Wahlbergson, and Hendrick Terbrugghen and the Post-Impressionism tradition. Painters typically deployed copper at an average of 6% of the canvas, with dark red at 4%. Third colors most often completing the combination include Eerie black (#1B1B1B), Isabelline (#F4F0EC), and Kobicha (#6B4423).