The Colorless Blender’s transparent alcohol-based solution is the base of all Copic inks. The Colorless Blender is an art tool on its own and should not be thought of as just a blending tool! The name ‘Colorless Blender’ may be misleading because the marker doesn’t blend colours as much as it moistens the marker dye so it can be manipulated. This clear solution lightens Copic inks by pushing colour through the back of the paper. If stored properly — out of direct sunlight and away from extreme heat or cold — a bottle of Colorless Blender will last for many years.

More amazing info on the Copic Colorless Blender can be found here: https://www.copicmarker.com/pages/colorless-blender-101