Broken window glass can be replaced by regular glass or by plastic unbreakable glass, usually an acrylic. Before starting to replace broken glass, put on a pair of gloves and a pair of glasses. It is easy for bits of glass to chip and fly. Glass, in both wood and metal frames, is normally held in place by a mechanical fastener. In wood these are usually glazers points, a small triangle of thin metal. In metal spring clips are used. Putty or glazing compound is then applied to keep out rain. The following steps are suggested for replacing broken window glass:
- Carefully remove all pieces of glass being careful to clean up the area around the window to prevent injury and cuts. Use pliers to grip pieces of glass still in the window.
- With a chisel or jackknife, remove the old putty. Be careful not to gouge the wood frame. As you proceed around the frame you will find glaziers points (small steel triangles) in wood frames or spring clips in metal window frames. Save the points or clips. Be sure all old putty is removed so the glass will slide into place easily.
- With sandpaper or a rasp, clean off bits of putty which remain on the wood or metal sash.
- Paint the frame with an oil based wood preservative or an oil base primer. This seals the wood surface under the putty and prevents the metal frame from rusting. A fast drying primer is the most convenient.
- Measure the size of the glass with a yardstick or folding rule. A steel rule may sag causing errors in dimensions. Allow 1/8" clearance on all sides so reduce each measured dimension by 1/4". Buy the glass cut to the correct size.
- Put a thin ribbon of glazing compound in the groove on the frame for the glass to rest on. Keep the thickness of this glazing compound fairly uniform so when you press the glass down into the compound it will not crack.
- Install the glass, press it onto the glazing compound and insert the glaziers points (small metal triangles) which you removed. Push these in with a large screwdriver. If you use a hammer be careful not to break the glass. The points should be placed every 6" to 8". The spring clips for metal windows should be inserted in the holes provided in the steel frame.
- Knead the glazing compound and form it into strings no bigger than a pencil. Lay a string of compound along one side at a time and force it onto the glass and wood frame with the tip of a putty knife. Smudges from the compound can be removed later with a cloth dipped in mineral spirits or turpentine.
- After the glazing compound has dried, paint it to finish sealing the seams between the glass and the compound, and the wood and the compound.
This article has been contributed in part by Michigan State University Extension