Replacing a pane of glass is a fairly simple task, as long as you follow some basic rules and work safely. The task obviously gets more difficult the larger the pane is and the higher it is located. Before you start removing glass and applying putty, you need to measure the opening where the glass will fit and have a new pane cut by a glass supplier. The supplier should be able to advise you what thickness of glass you need for the size of the opening and the type of frame.
Removing Broken Glass
The first thing you need to do is to clear the frame of any remaining glass. Make sure you wear thick gloves and eye protection when doing this. Place a dustsheet on the ground both inside and outside of the window to catch any fragments of glass and then score all the way around the broken pane with a glass cutter, close to the putty. Tap the glass with a hammer to break it out of the frame, trying to keep the pieces as large as possible. Now remove the old putty with a chisel and take out the remaining glass and glazing sprigs or tacks. Remove any dust from the window rebates and paint the frame with a coat of primer.
If you need to leave the window unglazed overnight or for any long period, you can fill the hole with a piece of hardboard cut to size and nailed into the frame, or you can cut a small sheet of thick polythene and nail thin battens of wood around the edges to hold it onto the frame.
Choose the correct putty for the type of frame you are working on. Linseed Oil or Acrylic Putty should be used for a wooden frame and Metal Casement or Universal Putty for a metal frame. With either type of putty, you should work it in your hands for a little to soften it up. Now run a thin bead of putty around the rebate and press it firmly into the corner.
Inserting The Glass
Now carefully insert the new pane of glass, pressing the edges gently into the putty (never press in the middle of the glass). Use a small hammer to tap the sprigs or tacks into the frame so they hold the pane of glass. Make sure they are tapped in enough so that they will not show through the putty about to be applied. Alternatively, if you are working on a metal frame, bend the clips to hold the glass in place.
Run a second bead of putty around the edge of the glass and press it in firmly. Using a wet putty knife, carefully bevel the putty so it matches the rest of the windows. Alternatively, you can choose to use beading to hold the pane in place, bevel the corners and use tacks to pin it in place. Use a punch to knock the heads of the tacks below the surface and finish off by painting or varnishing as required.