Remove window glass whole by taping an X across the pane, taking out the stops with a putty knife and pry bar, softening and scraping the old putty, and lifting the pane out to carry it on its edge, because glass is much stronger against edge-on force than against flat bending. Tempered glass from car windows and shower doors cannot be cut and shatters into small cubes, so use it whole, and assume old putty and window paint may contain asbestos or lead.
Part of Building Material Recovery
Panes of glass can be made from sand, but a salvaged window saves a great deal of furnace work. The risk in recovering one is to the person, and the chance of recovering it intact is mostly decided in the first few minutes.
An Unbroken Pane Is Worth More Than The Frame Around It
Window glass is remarkably difficult to produce from scratch. Even small panes serve for greenhouses, cold frames, solar water heaters and window replacement (parent article).
What You Need
- Duct tape.
- Putty knife, flat pry bar and a hammer.
- A hair dryer or heat gun if power is available.
- Cut-resistant gloves, eye protection and boots.
- A glass cutter and a straightedge, for trimming plain glass.
- A padded place to stand panes on edge, in a rack or leaning against a wall with a soft base.
Method: Tape, Free, Lift, Carry
Step 1: Tape an X across the pane with duct tape. If it breaks, the tape holds the fragments (parent article).
Step 2: Check the frame for hazards. Old glazing putty in pre-1980 buildings may contain asbestos, and old window paint may be lead-based, so do not sand, grind or burn them; see Asbestos, Lead Paint & Other Hazards.
Step 3: Remove the window stops, the strips of wood holding the glass in the frame, with a putty knife and a pry bar (parent article). Work slowly and do not lever against the glass.
Step 4: Free the putty. Old glazing putty can be softened with a heat gun or hair dryer and scraped away (parent article). Without power, score and chip it out with a chisel, working away from the glass. Wet it first if dust is a concern.
Step 5: Lift the pane out with two hands on opposite edges and set it on a padded edge.
Step 6: Carry it vertically, on its edge, not flat (parent article). Two people for any large pane.
Step 7: Trim if needed. To cut plain (annealed) glass, score once with a glass cutter along a straightedge, then snap it over a table edge. Do not re-score.
Tempered And Other Glass
Tempered glass (car side windows, shower doors, some commercial windows) cannot be cut and shatters into small cubes rather than dangerous shards. It is useful as it is, for tables, shelving and cold frames, but it cannot be resized (parent article). Tempered panes are often marked with a stamp in a corner; do not try to cut one, since it fails all at once.
Laminated glass (windshields) cracks but holds together; see Vehicle & Machinery Cannibalization.
Bottles and jars. Collect intact ones for storage; wash them thoroughly and never reuse a container that held chemicals for food or water.
Common Mistakes
- Cutting tempered glass. It explodes into cubes.
- Prying against the glass. It cracks.
- Carrying a pane flat. It bends and breaks.
- Skipping the tape. Fragments scatter if it breaks.
- Sanding old putty or paint. It makes dust that may be asbestos or lead.
Safety
Glass cuts, tempered glass bursts, and old putty and paint may be toxic
Wear cut-resistant gloves, eye protection and boots for all glass work, and never carry a pane under your arm or flat. Tempered glass can shatter into a mass of small cubes with little warning if stressed or struck at the edge. Do not sand, burn or dry-scrape old putty and window paint. If a pane breaks, keep other people away and clean it up with a damp cloth or brush, not bare hands.
What’s Next
- Learn next: Flat Glass — making panes when salvage runs out
- Combine with: Hardware & Fasteners — removing the frame hardware