Self-inking stamps have a built-in ink pad. A patented spring device automatically re-inks the die with your image between each impression. In slow motion, you can watch the rubber stamp as it flips up and then down against the ink pad – with each impression. In general our self-inking stamps use a water-based ink. Even though they typically need to be re-inked more than pre-inked stamps, the re-inking procedure is remarkably easy and mess-free.