I know the original post is nine years old, but I found this post through a Google search about painting latex over spray paint (which I am encountering in a totally different situation.) I do have experience with painting over spray paint on a metal door 4 years ago (with great success) and we are once again doing this right now, so I thought I would share our technique/product in case someone else is in this situation. We used (and are once again using) Rustoleum Professional High Performance Enamel in a CAN (rather than spray paint.) It is an oil-based paint for metal. When we first used it 4 years ago, we were applying over faded spray paint. Spray paint is pretty durable for an exterior door but can fade terribly. We sanded any rough spots or scratches, and then used a spray primer over any bare metal. We waited a full 24 hours to do any more work. Then, we used a very fine nap small roller to apply the paint, using a small brush where needed (as it was a panelled door.) One coat of a deep red gave beautiful coverage over white primer. We waited a full 24 hours to rehang the door. The door today is as glossy and flawless as it was 4 years ago when we painted it, and it gets full sun, with temps well below freezing in the winter, and hot summers. This time, we're painting over another spray-painted door (should have done them all at once 4 years ago, but didn't.) We're also painting over a door which has never had anything but the factory-applied primer. In both cases, we are again sanding as needed, priming if needed, and applying the oil-based enamel with a fine nap roller and brush. This paint is durable, gives great coverage, and is beautiful.

All my doors are now done with the Brilliant. I started with screen doors which look like new after 2 years. This summer I redid the front door with it and the entire front porch (which had 2 y.o. paint & looked terrible) and front trim. We'll redo the trim in back next year. I am told it's expected to hold up for 8 years. The paint also comes in pints. One pint of the blue did all the trim on 2 screen doors and 2 coats of my front door with some left over. It is excellent to work with and has excellent results. If you want the Euro door look (I love the English doors as well) this is the way to go.

I currently have mix of all the kinds of doors. I have a 20 gauge steel door going into the garage. It's on the west with little overhang. It bakes. I purchased it primed and painted with regular exterior latex and looks fine (other than brushstrokes) and it's 4 years old. It has no dents but I think it the gauge of the steel has a lot to do with that. Our previous door was a lumber yard grade door that was 24 or 26 gauge and had dents like crazy. I have a oak grain fiberglass entry door with 1/2 glass. Again I opted against factory finish and did it myself. I painted the outside black and stained the inside. This is on the north with a storm door and large porch overhang. Door is holding up great. Yes, the wood grain isn't as realistic as a real wood door but it still looks great and it's fooled a few people from a distance. And for our patio door we have a real wood door with vinyl cladding on the exterior. This door the exterior was factory finished and the inside once again I stained. It replaced a solid wood patio door that was held together by paint and caulk. It faces the south and had deteriorated to the point we could see daylight. I've been happy with all my doors. All from different manufactures but all from a reputable Door/Window company.

For what it's worth, we've had regular (not "High Gloss Trim & Door") Glidden paint on most of the interior and all of the exterior of our home for over 11 years and it's held up very nicely. We used the semi-gloss finish on our upstairs trim and doors. Most of it was sprayed on (not brushed) by our builder's contractors, though we've brushed the semi-gloss onto crown moulding and bead board we added about 8 years ago and painted walls/ceilings ourselves with eggshell/flat. I don't see a quality difference between the walls we've painted ourselves with Glidden vs. those we've painted with Sherwin Williams or Ben Moore's Aura and Regal paints. I don't have an allegiance to one brand of paint and am VERY picky about color, so choose brand depending on which color I like best for a space. I happen to like a lot of Glidden's colors which is why I have a lot of experience with their paints. I think all high-gloss paints are difficult to roll on and get a perfect finish, so wouldn't necessarily blame it on the brand... My husband stained and finished all of our downstairs wood work and doors and originally tried to use a high-gloss clear coat over the stain (I don't remember the brand-- not Glidden though), but decided to switch to a satin clear coat because it was so much easier to apply and get an even finish. The areas where he first applied the high-gloss clear coat (and then went over them later with the satin) don't look as nice as those with just the satin clear coat. He did remove all the doors to finish them horizontally (not the trim work and built-ins).