Window cleaning is an important final step in finishing off construction of a building. This fact is sometimes ignored, and improper cleaning results in significant damage to the new windows. This in turn leads to a lawsuit. The glass association of North America (GANA) has published a bulleton to instruct as to the proper window cleaning procedures, and it strictly prohibits the use of metal blades. Above are photographs of two examples of the type of window damage caused when blades are used to clean windows on new construction. This damage was discovered during a window damage failure analysis. These windows are two of over 1000 showing window scratching from window cleaning damage. The parallel nature of the scratches indicates that dirt was caught under a metal blade and dragged across the window and scratched the surface.