How to paint wood that is half painted and half bare (chipped off paint)?

I would scrape away loose edges with a paint scraper or five-in-one tool, scrape away loose edges of the painted area. Apply Wood Filler. Allow Wood Filler to dry. Sand Down the Wood Filler. Check for Smoothness. Apply the primer on the Bear wood then undercoat the whole window allowed to dry and then apply topcoat

Hi Richard - we've dealt with just this problem recently on an old Victorian house.... Use your scraper / filler knife to remove all that is flaking / loose. Smooth with sandpaper the boundary between paint and bare wood (you should feel no lip when you've done a good job). Sand the rest of the paintwork for a good key. Prime it all Paint it all. If you can use a satin finish it will mask most imperfections - a high gloss will accentuate them. Tip: I don't cut in on the panes - let the paint go (a little) over the glass for complete coverage. Then when fully dry, scrape back with a blade / window scraper for a clean line. I hope this is helpful Kind regards Passion 4 Property

I would take more time to strip complete , sand it with fine paper , prime , undercoat x2 coats and two full coats finish .

Strip back with a 7 in one paint scraper all loose and flaking paint. Then feather down all remaining raised areas until smooth. Touch in with a primer to all bare areas then one coat of primer/undercoat combined to complete window to give a consistent covering then apply a Satin finish, one or two coats as your preference