How to Paint a Wood Window Sash
Painting a wood window sash is a great do it yourself project that can give you beautiful, satisfying results with a bit of time and effort. You don't need to be an experienced painter to get great results.
The first step is to remove all old hardware for blinds, curtain rods and the window locks. Keep them if you don't plan to replace them. You may notice a build up of paint around where these were installed if the house is old and has had many coats of paint. Use sandpaper to sand these down. Heavy build up can be scraped away with a putty knife.
Using sandpaper, sand all the old paint drips, peeling paint, brush marks and scrapes and scratches in the paint until the wood is smooth. If you can't see the smoothness, try closing your eyes and slowly running your hand over the wood. You will be able to feel places you've missed. Then if there are deep groves fill in with wood putty and sand smooth after it dries. Then using painters tape, mask all the areas where wood meets walls or window glass.
Next, use a good oil based primer and prime the entire surface of the woodwork. This is very important in older homes as it will seal bad paint jobs and give you a nice base to apply paint. It will also help your paint adhere well. Check for smoothness again.
Last, apply a good latex gloss paint per the manufacturers instructions on the can. When dry, scrape away any paint on the glass and you have a great job completed.