A frottage, like a "rubbing", is an image that has been drawn without ink into a forgiving material (paper, wood, etc.), and rubbed with a dry media, such as graphite, crayon, or charcoal, to pick up the image.
In the 1910s Xavier Martinez created the color monotype “Valkyrie of the Sea,” an image of a long-haired woman riding a fish through the deep ocean, perhaps on a valkyrie’s journey to retrieve a fallen warrior for transport to Valhalla. In addition to the monotype, two impressions done in frottage - made around the same time and exploring the same topic - were created by Martinez, of which this is one. Another frottage of a nude woman dancing appears to have been done at the same time in the same format, perhaps in preparation for a series
.Figures from Norse mythology, valkyries are akin to sprites, and their purpose is to choose which warriors will live or die in battle; of the dead, they take half to Valhalla; the other half are given to the goddess Freyja. One such telling describes Sigrun, a valkyrie who arrives at her destination through air and sea to address the warrior Helgi before he sails to battle.