The key to beautiful and long-lasting wood windows is maintenance. Inspecting and cleaning monthly will prevent damage and allow you to recognize problems early, when it’s easier and cheaper to repair them.
With these types of windows in particular, location is important. Windows on the south side of your home or more vulnerable to weathering. Over time, build up of moisture, dirt, pollution, and even soot can make the finish deteriorate so it’s important to treat the wood, clean it routinely, and treat it again as needed.
Use a dry cloth with no abrasive characteristics to remove the top layer of dust and dirt. Taking the time to do this first will make the rest of the process more efficient. Check for cracks, peeling, and mildew. If you notice any spots where the finish has come off, retreat them as soon as you can because you don’t want your wood to go without protection.
You don’t need any special or expensive products for your windows. To wash the frame, use mild detergent and a soft cloth or sponge with warm water. Make sure it is simply damp rather than soaking wet, you don’t want any rogue water to run down the frames to seep into cracks or the windowsill. Rinse and wring out the cloth often, and keep the water clean by replacing it when necessary. Wipe with a damp cloth after cleaning to remove soapy residue, and then again with a dry cloth to remove excess moisture.
Use glass cleaner or vinegar mixed with water to spray the glass, then clean with microfiber or newspaper and polish the glass with a dry cloth to eliminate any streaks.
To refinish any parts of the frame that need it, sand those areas with a very fine sandpaper. Fill any cracks or uneven spots with wood filler and then smooth it over with a putty tool. Let the wood filler dry overnight. You want to be particular with which finishes you choose. Some paints block the sun, but trap in moisture. With wood being prone to decay, you definitely want to avoid this. Go for a latex or oil-based enamel paint intended for outdoor use, or a semi-transparent stain with protective abilities if you want a more natural look. Apply one thin coat of whatever you choose and then leave it to dry for about two hours before adding a second.