Windows are leaking where panes meet

I live in an older home, and have wooden windows - aluminum sides - opens by springs. Each window has 6 panes in it, and it appears water is leaking through where the panes come together. From the outside, it looks like the caulking (?) where the panes come together is moldy and cracking, possibly allowing water to leak through inside. Can this caulking along the panes on the outside be replaced. Is this what normally is done, or are the windows replaced? The windows are in good condition except for this. If the caulking can be replaced, what should I use, and how long does this take? I will most likely have to do this for all the windows in the house. Thanks.

 

The "caulk" is called glazing putty or compound. Look for a product called Dap 33. You must first remove all the old putty, which CAN be a real chore. There is a tool call a Prazi putty chaser which basically is a small router type bit that runs in a handle and you hook into an electric drill. It will route out the old putty fairly well.

The new putty you roll in your hand to warm it slightly and make a "roll" of putty about the diameter of a large pencil. Using a putty knife, you work the roll against the glass, making a slope away from the glass. Let the putty dry a few weeks ( it is oil based), then paint over with a good exterior paint.

It's a LOT of work if you have very many windows.....I'd consider replacements, personally......but I'm sorta prejudiced in that direction