Uni Liquid Chalk Markers utilise water-based pigment ink so you can mark on windows, glass, mirrors, plastic and metal surfaces with ease. The ink won't wash off in the rain, yet is easy to remove with a damp cloth. For permanent application the markers can also be used on chalkboards for a bold statement. This marker has a bullet nib for writing and drawing. You can use it on glass, mirror, windows and metal. The ink is water based and can be washed off with a damp cloth. The colour of the ink is black. The ink is removable on non-porous surfaces. It's recommended to store these markers horizontally when not in use.