How to remove glass putty from window

When installing new glass, you must remove excess glass putty for professional work.

You must remove old putty when removing broken glass or removing old ones. Lucky for you, to remove the putty – even old, hardened putty – window glass is quite a simple task.


  1. Apply heat to soften old, hardened putty by removing broken or old panes. Set a dryer or hot air gun in its highest position. Keep the nozzle a few inches away from the putty. Sweep back and forth over a 6 inch section of putty. Prod the putty heated with the finger every 30 seconds or less. When it starts to soften, you are ready to scrape away. If you are going to remove freshly applied putty, skip this step.
  2. Scrape frame putty with your knife. Keep the knife almost parallel to the glass structure while maintaining full blade contact. To remove excess new putty, start at one corner of the frame and slide the knife parallel to the frame until you reach the opposite corner. Remove the old putty, slide the knife toward the wedge frame the knife under the soft strip.
  3. Clean, putty residue. Clean the glass with mineral spirits to remove oil residue from the putty. Then clean the glass with denatured alcohol (do not touch the putty on the strip with the denatured alcohol).