Removing old putty and replacing it with new in a wooden window can be challenging. Often the putty has hardened or has been painted over.
Sometimes the putty on your windows wears out, even though the glass is still perfectly good. The glazer’s putty is what creates an air and water tight seal between the window pane and the window frame. If the putty deteriorates, the seal is no longer functional. You can replace the putty on your windows with just a few simple tools.
Scrape away the old putty. Use a putty knife to break the putty into small pieces for removal. This helps avoid splitting the wood frame. Soften stubborn putty with a heat gun or hair dryer. Work on a small portion at a time. Make sure to remove all small bits of the old putty.
Remove the glass. If the glass is intact, carefully press from the opposite side to remove it from the frame. Set it aside.
Scrape away any remaining hunks of putty. Use the putty knife to remove any traces of the old putty that remain after you remove the glass.
Apply linseed oil to wood to help keep the putty from drying out too fast. Use an old cloth and wipe the part of the frame where the window glass rests, and where you removed the old putty.
Knead the putty until it is soft and pliable. Apply a 1/16-inch layer of putty around the frame in the slot where you removed the window pane.
Re-insert glass on top of putty. Press down firmly on glass, using even pressure.
Insert a glazer's point every 4 to 5 inches around the frame. These hold the glass firmly in place in the window frame. Lay glazer's point flat on the glass with the "point" towards the frame. Tap gently with a putty knife to get it started into the wood. Use the glazing tool to finish driving the glazer's points into the frame.
Knead more putty if necessary. Make putty "rope" by rolling between palms. Lay putty rope into slot where window pane rests, directly on top of the glazer's points. Use a putty knife to push the putty into the slot and create a seal between the window glass and wood frame. Don't put it on too thickly.
Smooth the putty with the glazing tool. Hold the tool at a 45-degree angle and use smooth, even strokes to spread the putty out. Don't let the putty extend more than ¼-inch onto the glass. You shouldn't be able to see the putty from the other side of the window.
Paint the putty to seal out the weather. Some brands can be painted immediately; other brands of putty require a curing period before painting. Read and follow manufacturer's instructions.