Replacing a Pane of Glass
Renovation pro Mike Litchfield explains how to cut, set, and glaze a new pane in a wood window.
Wear safety glasses and gloves when removing old glass and putty (glazing compound). Try not to damage the sash when removing putty. Although a glazier’s chisel will remove most putty, try to soften tougher stuff with a hair dryer first. If that doesn’t do it, lay the sash flat and pour a small amount of rubbing alcohol on the putty and let it sit overnight. (Do not combine heat and alcohol.) After removing old putty, glazier’s points, and damaged glass, sand the frame lightly, using 180-grit sandpaper. Prime and paint bare wood before proceeding.
To cut glass, pull a glass cutter along a straightedge as shown in the photo below. After scribing the glass, gently rap the ball end of the cutter along the underside of the cut until a clear line develops. Then, holding the cutline directly over a table edge, snap the waste portion free. If the waste piece is too small to grasp, use glass pliers. Cut the glass 1⁄8 in. smaller than the length and width of the frame opening.
Cutting Laminated Glass
Laminated glass is increasingly popular for its impact-resistance and sound-deadening qualities. Because there is a plastic core between the two layers of glass, however, there’s a trick to cutting it. Using a glass cutter, score both sides of glass. Then squirt a small amount of ethyl alcohol along the cut on one side and light it. This melts the plastic core. Then, using a pair of glass pliers, snap away the excess.
Using a caulking gun, apply a bead of acrylic latex with silicone around the perimeter of the frame. Place the glass in the frame, and press down so it seats evenly in the sealant. Next, use a putty knife to push glazier’s points into the muntins to secure the glass; space points every 6 in. around the perimeter, using at least two points per side. Glass in metal-frame windows is typically held in place by metal spring clips, which can be reused.
When the glass is secure, apply putty. For the best combination of skin protection and dexterity, wear nitrile disposable gloves for this operation. Scoop out a generous palmful of putty, and knead it until it is soft and pliable. Roll it up into a fat snake, then use your thumb to press the putty around the perimeter of the pane. You’ll trim excess putty, so use a lot to ensure a good seal. The pros apply putty and trim it in one sweep, but the rest of us should do it in two passes. Once a side has been puttied, rest one point of the putty knife on the glass, and holding the blade at a 45° angle to the glass, pull the knife steadily to cut a furrow through the putty.
Excerpted from Renovation, 5th Edition (The Taunton Press, 2019) by Michael Litchfield and Chip Harley