An aqueous penetrating ink includes a pigment and a water-soluble dye. The ink also includes a humectant in which the water-soluble dye is to be at least partially dissolved. The humectant is present in the ink between 20 percent by weight and 70 percent by weight. This amount of humectant results in a slow evaporation rate. The ink also includes water, making it suitable for use with some inkjet printers. Because the pigment is not dissolved in the humectant or the water, it forms an image on the surface of a printed side of a substrate. The slow evaporation rate of the humectant allows it to carry the ink through a thickness of a substrate so that it is visible on a non-printed side of the substrate.