Although this might seem like a simple job, painting wooden window frames should always be completed in a certain way. You have to take into account the fact that you will want to close the window as night approaches, and if the areas that touch are still wet, they will mark each other, or worse, stick together.
Painting Casement Windows
Casement windows are those which are hinged on the sides and open like a door. Your first job should be to remove the stay and the catch. Without the stay and catch, the window is in danger of swinging about as you paint. To stop this, drive a small screw or nail into the underside of the window, hook a length of wire onto it and hook the other end into the screwhole of the catch.
You now need to consider the order of painting, which should always be started in the morning to allow time to dry. First you should paint the actual frame, starting with the areas which will be touched by the window as it closes. Next you should paint the top and bottom horizontal rails and then the vertical stiles (the outer frame of the actual window). Once this is done, paint the glazing bars, using a paint shield (or masking tape) to keep paint off the glass.
When the paint is touch dry, you can replace the catch and stay.
Painting Sash Windows
Sash windows are tricky to paint as they have two sliding panes which overlap each other. Getting to all of the areas that need painting needs some planning. This guide assumes you are painting the window from the inside, meaning the bottom sash slides in front of the top sash. As with casement windows, start early in the day to allow plenty of drying time before the window needs to be closed.
Raise the bottom sash fully and pull down the top one about halfway. Now paint the bottom meeting rail of the top sash (the meeting rail for each sash is the bit where the catch is found) and the parts of the vertical stiles which are accessible. Reverse the position of the sashes, leaving a small gap top and bottom. Finish off the painting of the top sash (the rest of the vertical stiles and then the top rail) and then paint the whole of the bottom sash.
Now start painting the frame, only leaving the runners (the grooves the sashes slide in) free of paint. Leave the paint to dry for as long as possible before closing the window for the evening. The next day, the paint should be nicely dry and you can start on the runners. Pull both sashes down to the bottom and paint the inner and outer runners. Leave to dry for a few hours and then move both sashes to the top and paint the bottom section of the runners.
If you are painting the outside of the window, start with the bottom sash instead of the top one. Apart from that small difference, you should follow the same order of painting.
Protecting the Glass
When painting window frames, it is important that the paint overlaps onto the glass very slightly (2mm or so) as this helps to prevent moisture seeping between the glass and woodwork. The easiest way to do this is to use a strip of masking tape. Stick the tape to the glass, leaving that important 2mm gap between the tape and the frame. Let the paint dry slightly and then carefully peel off the tape. If you leave it until the paint is full dry, the tape may pull some of it off.