An undertone, figuratively speaking, is a characteristic or quality that is present but not clear or obvious. When talking about inks we talk in terms of warm or cool undertones. The undertone of an ink can be revealed when the ink is spread thin so that it is less dense, and light can filter all the way to the substrate and bounce back up through the thin film of color. As you can see from this comprehensive undertone test created by Jane from our Fine Pens Department, not all black inks are the same. There is a whole spectrum of undertone colors. We sometimes refer to this as a tint. A black ink may tint green, warm brown, or purple depending on its undertone. Undertones can be unpredictable and mysterious and once you become aware of them, you'll start seeing them everywhere! Visit our Fine Pens Department to see more ink swatches like this one!