Shoe polish was once used in the Auto-cross scene to mark the windows of racers. It is now banned from many events but car dealerships and private sellers still use shoe polish to advertise the sale of a car on the windows. Shoe polish removal from glass is time consuming but can be done cheaply.
Wet down the window or area where the shoe polish has been placed. The polish likely won't come off by simply being wet down, but it makes the entire process a bit easier.
Put on gloves to protect your hands.
Start removing the shoe polish with a straight razor. Lay the razor as flat as you can against the window and work in an upward motion over the shoe polish.
Be very careful not to drag the side of the blade against the window as you will scratch the glass. Slowly go over each area of shoe polish in an upward motion until it has been removed.
Douse the window down with Windex (or any glass cleaner) and wipe it off using one of the rags. This will help remove any flaking and minor pieces of shoe polish.
Repeat Step 5 with clean rags or towels to remove any remaining flecks.
