Windows, glass doors and other glass surfaces in the vicinity of a spray paint job are vulnerable to overspray, but it is usually easy to remove. On the other hand, your store windows may have been the object of graffiti vandalism, or you may need to update painted signs where paint removal may not be as easy. Cleaning paint from windows takes a combination of scrapers along with soap and water and sometimes -- solvents.
In most cases, you can remove overspray from clear glass by scraping it off with a razor blade -- especially true if the overspray is light. Let the overspray dry before trying to remove it -- wiping wet paint only smears it and makes removal more complicated. Use a razor scraper, which is a tool with a handle that accepts a standard single-or double edged razor blade, and angle the tool at about 30 degrees relative to the glass while scraping. Dried paint spatters usually pop off in a flash -- it takes less than a minute to clean a 12-by-12 inch pane of light overspray using this method.
Heavy Overspray and Opaque Films
When you have to remove an opaque film of spray paint from a pane of glass, it's still better to wait for it to dry than it it to try to wipe it off while it's wet. If the film is continuous with a frame around the glass, score a line between the glass and the frame with the edge of a razor scraper or utility razor to prevent lifting the paint from the frame when you remove it from the window. In most cases, you can remove paint splatters with the same scraping technique you would use for light overspray, but it will probably take longer, and you may have to return to already-scraped areas to remove residue.
Frosty or Pitted Glass
Scraping frosty or pitted glass with a razor blade is a good way to scratch the glass, so scrape with a plastic paint scraper. In this case, the paint is easier to remove if it's soft. If you can't get to the paint before it dries, you may be able to soften the paint with soapy water -- a solution of 1 cup vinegar per gallon of water or spray metal lubricant. If none of these work, use isopropyl alcohol or -- as a last resort -- acetone or lacquer thinner. After scraping the softened paint, remove the residue with a rag moistened with the solvent that softened it.
If you don't catch it in a tray or bucket, the paint you remove from the window will fall to the ground, where it may get wet. Let paint chips dry before vacuuming or sweeping them, or you may end up simply grinding paint into the floor. Before removing paint from an interior window, cover the floor with newspaper or a dropcloth to prevent this from happening. After you've scraped or wiped all the paint off the glass surface:
• Clean the glass with soapy water to remove residue • Dry the glass with a rag • Spray the glass with glass cleaner • Squeegee the glass