The ink in the edding Securitas UV marker is permanent, as the marker is primarily intended for concealed marking of objects for anti-theft purposes. To remove the ink from closed surfaces such as window glass, you can use the edding 8860 cleaning paste. In this case, the success of the cleaning process depends to a large extent on how long the marker has been on the surface and what weather conditions it has been exposed to. If used for a short time, the marking can be removed without leaving any residue.