Lightly sand the "rabbet" (the L-shaped groove where the glass sits) to remove any leftover debris or old paint.
Measured to fit (minus 1/8 inch for expansion) Glazing compound: To seal the glass how to replace broken window pane
Apply a very thin bead of glazing compound (about 1/16 inch) around the frame's inner edge. This creates a cushion and a weather seal for the glass. Set the glass: Press the new pane firmly into the bedding. Lightly sand the "rabbet" (the L-shaped groove where