Learning to replace glass in old windows is an important skill for owners of older homes, since restoring the original windows will add value and maintain the integrity of your home. One advantage to old wooden windows is that they were designed so that the home owner could perform repairs and maintenance. Glass is held in the window sash frame with metal points and glazing putty. The putty and points are removed when a pane of glass is broken and the glass can be removed.
Place the old window sash on a work surface with the glazing putty facing up. The sash is the wooden window frame that holds the glass.
Scrape the glazing putty out from around the glass in need of replacement. Carefully work along the edges of the putty until you can remove it with the edge of the putty knife.
Pry out the glazier's points from around the perimeter of the glass with the tip of a flat head screwdriver. Use the edge of the wood around the glass as leverage to push the points out of the wood.
Apply even pressure on the back side of the glass and carefully remove it.
Brush the wood where the glass rested with a wire brush to remove any loose debris. Sand around the wood with a scrap piece of sandpaper.
Apply a bead of caulk around the wood where the glass rests. Insert the replacement glass into the window sash. Press down on the glass to firmly seat it in place.
Push glazier's points into the wood around the window with the tip of a flat head screwdriver into each spot where you removed one.
Glaze around the edge of the glass to fill in the joint with glazing putty. Apply the putty with a putty knife at an angle that extends from the edge of the sash to the glass.