Pilot Pen has developed a thermo-sensitive ink which disappears once it reaches a temperature of more than 65°C. This can be achieved by using the rubber attached to Frixion Pen. Rubbing the ink using the rubber creates friction and heat, which causes the Frixion ink to disappear. If you have accidentally left your notes written with the Frixion series in a hot environment (e.g. car parked under the sun), don’t worry, the ink will reappear if you store your notes in a low temperature (i.e. below -10°C).