All Trodat self-inking rubber stamps have an integral stamp pad (ink cartridge) that can be easily replaced when your stamp is no longer creating a crisp impression. Once your imprint starts to lose its sharpness, simply swap with a Trodat replacement ink pad to make your stamp as good as new. Trodat ink cartridges and ink pads are available in the standard colors of black, blue, red, green, violet and for daters/numberers in blue/red. The ink in the cartridges is manufactured with a water base, and does not contain any toxic substances, acid, formaldehyde, or heavy metals. The ink in Trodat ink cartridges is hygroscopic: it regulates itself by absorbing moisture from the air, therefore it does not dry, and allows prolonged usage over extended periods of time.