An ink composition for a reversibly thermochromic stamp including a reversibly thermochromic microencapsulated pigment encapsulating a reversibly thermochromic composition including: Component (A): an electron-donating color-developing organic compound, Component (B): an electron-accepting compound, and Component (C): a reaction medium causing reversibly an electron transfer reaction between the Component (A) and the Component (B) in a specific temperature range, water and a thickener.

An assembly includes a master for imprinting of micro-structures and nano-structures. The master has on its upper surface an active area with relief structure for imprinting of the micro-structures and nano-structures, and the master has a thickness d.sub.master. The assembly includes frame pieces arranged around and flushing along the outer circumference of the master, with the frame pieces having a thickness d.sub.frame. The thickness d.sub.frame of the frame pieces deviates from the thickness d.sub.master of the master by at most 250 m. A a flexible stamp has improved alignment.

An assembly includes a master for imprinting of micro-structures and nano-structures. The master has on its upper surface an active area with relief structure for imprinting of the micro-structures and nano-structures, and the master has a thickness d.sub.master. The assembly includes frame pieces arranged around and flushing along the outer circumference of the master, with the frame pieces having a thickness d.sub.frame. The thickness d.sub.frame of the frame pieces deviates from the thickness d.sub.master of the master by at most 250 m. A a flexible stamp has improved alignment.

An example ink cartridge for a stamp may comprise an image-forming component, a first ink-storage component made of an ink-absorbent material, a second ink-storage component made of an ink-absorbent material having one or more channels in it, and a frame made of a rigid, non-ink-absorbent material. The frame may comprise a floor having one or more holes in it. The frame may comprise an outer wall along its perimeter. The outer wall may extend up from the floor such that the outer wall is capable of retaining ink while the ink is being absorbed by the first ink-storage component and the second ink-storage component, thereby increasing the effective volume of the channel(s). The one or more holes may align with the one or more channels such that ink is enabled to flow through the hole(s) into the channel(s).

An example ink cartridge for a stamp may comprise an image-forming component, a first ink-storage component made of an ink-absorbent material, a second ink-storage component made of an ink-absorbent material having one or more channels in it, and a frame made of a rigid, non-ink-absorbent material. The frame may comprise a floor having one or more holes in it. The frame may comprise an outer wall along its perimeter. The outer wall may extend up from the floor such that the outer wall is capable of retaining ink while the ink is being absorbed by the first ink-storage component and the second ink-storage component, thereby increasing the effective volume of the channel(s). The one or more holes may align with the one or more channels such that ink is enabled to flow through the hole(s) into the channel(s).