hi Birdy, you can paint oil based paint over acrylic paint, but only certain water based or acrylic paint can be painted over oil based, your paint shop will be able to tell you, however for you to know what type of paint is on, then get a rag and dip it in methylated spirits, then rub it over the paint, if the rag becomes covered with the paint from the door then it's acrylic based paint, so any paint will do.
People are turning away from oil based paint, simply because acrylic paint washes out with water, rather than oil based you need turbs to clean the brushes, but what happens is that people can leave the brush in a jar of turbs and it may stay there for days, making it much harder to try and clean.
Just rub down any loss paint, wash down with water a couple of times and you're ready to paint, just put a drop sheet down under the door so no paint will get on the doorstep or on the carpet.
If it painted in oil based paint then rub it down, then wash a couple of times and the paint store will recommend an acrylic paint that will paint over oil based paint and dry as hard as a rock.
Mathy may join in as he works at a large hardware store. Geoff.
