They did this to prevent the glass from shattering everywhere if a bomb blast should occur nearby. Today, masking tape, sticky paper etc. is used by activists to prevent broken glass from making lots of noise when it falls and also to help prevent the mess of broken glass causing injury to themselves when they enter the building. Catapults Catapults and hard, heavy objects such as marbles, ball bearings or stones are used as a means to break windows as a distance for the purpose of economic sabotage. Glass etching fluids Used by activists in the animal liberation movement, glass etching fluid a quiet method of economic sabotage. Usually used on butchers windows or car windscreens belonging to companies or individuals involved with animal abuse.
Stickers are available that use adhesive that is very difficult to remove from glass.
Such stickers are used in some areas on windows of cars that park in no-parking areas. Posters or graffiti can usually be removed from windows without much effort and fairly quickly. One method of slowing down the removal of the slogan or poster and also necessitating the need to replace the glass, is to glue a sheet of glass over the poster or slogan directly onto the windows glass. This is probably not a very popular action since it may be difficult to achieve and also time consuming. A spring loaded center punch is a tool used to make a dent in metal before using a drill to make a hole.