If you’ve ever mixed paint as a kid, you probably remember how blue and yellow made green. The same kind of thing can happen in printing, when two inks overlap, they can mix to form a third color. This is especially common when using overprint. Overprinting means one color is printed on top of another, without knocking out the background. So instead of printing red on a white background, you might be printing red over blue. And when that happens, the inks blend—sometimes creating a brand new color. This new color is what we call a third color result.
Designers sometimes use overprinting on purpose to create layered, screen-printed effects. It’s a great way to add depth or create new colors without using more ink. But if you’re not expecting it or if it messes with your brand colors or readability, it can be a real problem. It can make text harder to read, change colors on logos or icons, or create mismatched tones. For example, if you print light blue over yellow and suddenly it turns green, that might not be the vibe you were going for.