Common Causes of Scratched Glass

Although a hands-on examination of the actual scratch is required to conclusively determine the cause, there are several commonly occuring trends. Listed below are some of the more frequent causes of scratched glass.

Interior Scratches
  1. Windows being delivered to the project with scratches already on the glass are rare, but this does occur. This damage usually occurs during window fabrication, in transit to the project, or during the installation of the window. At times, scratches are present between the glass (inside the IG unit). Obviously, this type of defect occured before or during the fabrication of the IG unit.
  2. Sheetrocking crews at times scratch the glass while removing splattered taping mud from the window. If they use a contaminated or rusted broadknife to remove this excess mud, scratches often result. The fact that the window is usually dry at this time also contributes to the resulting scratches. Touch-up crews doing texture patches are at times guilty of the same type of scratches.
  3. Texture crews, when sanding the walls and jams, can scratch glass if they let their sanding block hit the glass. This usually happens when a sanding block is used to sand the corners around the window jams where the wall meets the jam. The scratches are usually 4 to 6 in. from the sides of the window and 4 to 6 in. from the top. Rarely are scratches of this type found along the bottom of the window, as this area usually doesn't require sanding. This type of scratch is also rare if the walls are framed with 2 x 6 studs (instead of 2 x 4), as the sanding block is not as likely to come into contact with the glass.
  4. Painters and other tradesmen can cause scratches by resting their ladders and other tools against the glass.
  5. Unqualified window cleaners can scratch glass by not using proven construction window cleaning techniques to remove construction debris safely.
  6. The most devasting scratches are caused by tempered glass defects. Often there is fabricating debris from the tempering process on the glass surface, which will cause scratching over the entire surface of the glass during normal construction window cleaning. This subject is covered in more detail in the Glass Quality section of this site.
Exterior Scratches
  1. As stated above, windows being deliverd to the site with scratches are rare, but this does exist.
  2. Scratches can be caused by lathing wire being dragged across the glass during the installation of lathing wire and black paper.
  3. The application of plaster and stucco around the window, as well as plasterers attempting to remove plaster and stucco from the glass, can cause scratches.
  4. Painters and other tradesmen can cause scratches by resting their ladders and other tools against the glass.
  5. Unqualified window cleaners can scratch glass by not using proven construction window cleaning techniques to remove construction debris safely.
  6. The most devasting scratches are caused by tempered glass defects. Often there is fabricating debris from the tempering process on the glass surface, which will cause scratching over the entire surface of the glass during normal construction window cleaning. This subject is covered in more detail in the Glass Quality section of this site.

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