The following is a step by step guide to replace a broken window. It's not an extremely hard project, but you'll need a few guidelines to follow. One hint to remember is that if the window you are replacing is a large one you may want to remove the entire frame, lay it on a flat surface, and reinstall the glass in this manner.
The first thing you will need to do is to remove all of the remaining glass, being careful for small pieces that will be hard to see. Use heavy protective gloves if possible. Pull one piece of broken glass out at a time and have a bucket or other receptacle handy to place the old pieces in. You will need to remove and discard any putty that is connected to the glass pieces also. When this is finished, remove all old putty inside the frame. Use a putty knife or wood chisel for this. Don't try to remove large pieces of the putty at once, as you may crack the window frame. If the frame includes small metal triangles called glazier's points, you will need to remove them. After removing the old putty and metal pieces use the point of your knife to smooth out any rough areas or your new glass may not fit properly.
It's recommended that you take a cloth dipped in linseed oil, and wipe the entire frame down with it .Linseed oil helps keep the putty from drying out too quickly.
Next you will need to apply a very thin layer of new putty all the way around the frame where the new glass will be set.Try not to apply the putty too thick. A thin layer of putty on the window frame gives it a cushion for the new glass to be placed in. It also helps stop the leakage of air around the glass.
Now you are ready to install the new pane of glass. To do this you need to make sure the glass is the exact size you need. The new pane of glass should be a fraction of an inch smaller then the window area. Insert the new pane gently. Press into place firmly but carefully. While holding the pane in place, insert new glazier's points. Use the glaziers points all around the window for a good hold. Insert the new windowpane into the frame carefully. When this is finished slide a glazing tool along the frame.Mold some putty until it is pliable and smooth. Roll into strips about the size of a pencil. Lay the strip in the frame completely around the new piece of glass, and smooth with a putty knife.Let the putty dry slightly, and replace into window spot.
Some tools you might need for this project is a glass cutter, paint if you plan to repaint the window frame, a putty knife, gloves for protection, a chisel or knife and pliers.
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