Ploughman’s Pebble is one of two new inks that portray a characteristic we’ve never observed in our ink formulation adventures. Depending on the type of light in proximity to the ink it can change from a muddy classic brown all the way to a red shifted sepia. We’re not certain what wavelength of light causes this unique phenomenon as yet. In our experience the ink shifts to the sepia tone in daylight, and back to the muddy brown tone in most (though not all) indoor lighting.