@calgarycustomconcepts: I've been using Olfa knife blades for a long time to get paint, duck tape and goo off any glass surface. It takes ALOT of force to score glass. As long as you don't use the tip of the blade or a jagged, used blade this works great every time. Just don't use it on tinted side of windows or on vinyl decals! #LifeHack #carpenterknowledge #cleaninghack