"Made in honor of such friends as Marsden Hartley, Georgia O’Keeffe, Wallace Stevens, and Eugene O’Neill, these paintings, watercolors, and drawings used objects and wordplay to convey the life, rather than the likeness, of the sitters." (http://artgallery.yale.edu/publication/charles-demuth-poster-portraits-1923-1929)
In his poster portrait, Dove’s scythe has a red ribbon tied around it, a reference to his partner, the painter Helen Torr, who was known to friends as “Reds.” These witty details personalize the images, but only make sense if you know a bit about Demuth and his friends, which is perhaps why critics were slow to appreciate the cleverness of the poster portraits. (https://www.khanacademy.org/humanities/art-1010/art-between-wars/american-art-wwii/a/charles-demuth-i-saw-the-figure-5-in-gold) One site says the poster was done in poster paint (atheneum), another that it was done in oil paint (khanacademy). Who knows? Who cares?