There are very important rules that should be followed when it comes to window scraping. I highly suggest all the rules below to be carefully studied before you attempt this procedure. You can also see this done on the window cleaning videos page.
If these rules are ignored, you will end up with damaged windows.
If you need to scrape a window to remove hard, caked on debris, always use a professional window scraper.
These scrapers are specifically designed to be used on glass. Never use any other tools such as house hold razor blades, flat screwdrivers, box cutters, putty knives, scratchy pads, etc.
Always wet the window with soapy water before it is scraped.
Always inspect your scraper each time before you use it. Make sure the blade is not covered in any rust. Also check the corners of the blade to make sure they are not bent or chipped off. Whenever you’re in doubt, play it safe and put on a new blade.
Before you scrape the whole window, check to see that it is not leaving scratches. Do this by scraping a small section in the corner of the window. Then inspect closely at different angles.
Only use forward scraping motions like a plow. Scrape forward, lift the blade off the glass, pull back, and scrape forward again. Do not slide the scraper backwards. Doing so can trap debris under the blade. If this happens, it will scratch the glass.
Be aware of Tempered Glass. This type of glass may contain raised imperfections that will cause scratches if not cleaned properly!
Tempered glass is most commonly used in (but can be found anywhere) glass doors, side lights, windows located in stairways, over sized picture windows, next to bath tubs and showers, including shower doors and skylights. Most tempered windows or doors will have an etched labeled in one of the corners that says tempered or safety glass. Always test and check every window for this label before scraping.
Procedures for Scraping Glass
If it sounds and feels like the scraper is sliding across sand paper, and continues to sound this way even after the third or fourth scrape, do not scrape the rest of the window. The sandpaper-like sound indicates that this may be flawed or tempered glass that contains raised imperfections.
If tempered or regular glass that contains raised imperfections is scraped, it will cause scratches in the glass.
Once you have determined that it’s safe to scrape the glass, finish the whole window. Start with the edges. Scrape from the inside of the window towards the outside edge. Work all the way around the window with a one to two inch pattern. After the edges are scraped, start from the top and work your way towards the bottom. Scrape in a straight pattern of about four to five inches while overlapping each time. Remember to keep rule #5 in mind at all times while you work. If the window starts to dry out before your finished, wet it again and then continue where you left off.
Tip: When you are window scraping, scrape no more than two to three inches at a time. Do not ever scrape continuously from one end of the window to the other. If a piece of sharp debris does get caught under the blade, it will leave a scratch line all the way across the glass.
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