Remove as much glass as possible then using a chisel, remove the old putty and any glazing sprigs. Clean all the dust of the window.
Mould the new putty in your hands to make it soft and pliable. Place a layer about 3mm thick into the rebate around the window.
Press the glass firmly into the rebate. Fix in place with glazing sprigs about 250mm apart.
Apply more putty to the front of the glass and smooth it off with a putty knife to form a neat triangle that covers the glazing sprigs.
Leave the putty for about 2 weeks before you try to paint it.
Mohammed Patel, October 2003
