When I go to Home depot, Lowe’s, etc. all of the white baseboard molding seems to covered in the same kind of paint. I can surmise that it is some shade of white, but is the finish a gloss, semi-gloss, satin, flat, other? Just trying match some discolored stuff at my house. Thanks!
Typically molding is painted with gloss or semi-gloss because it gets dirtier being at floor level and can be washed more easily. Unless you’re good with a brush, use semi-gloss. Gloss glaringly shows off drips and streaks.
I prefer satin, it is still quite easy to clean and I prefer the less shiny effect.
But it’s true, if you’re matching something existing, it’s probably semi-gloss.
Roddy
Semi-gloss is pretty much standard on molding.
However, a factory finish paint job is sprayed on. It’s going to look a little different from a paint that’s brushed on at home. The factory finish will be slicker and shinier. Probably won’t notice unless the two moldings are installed side by side.
Carpenter here. The white base at the stores is not a finish coat, it is a primer coat, which is flat. It just saves you a step.
Usually the primer put on trim at the store is rolled on and will have an orange peel texture. It needs to be sanded off for semi or full-gloss. As the rule says: 90% prep 10% paint. To answer the OP the primer used on MDF trim is a latex primer like KILZ and is there mostly to seal the MDF and keep it from going crazy in the humidity.
When I painted for a living we would try to get the trim early so we could prime it and get a first coat on before the carpenters nailed it up. If you can do this it’s terrific, because it’s easier to fill nail holes and sand with an abrasive pad than to try and paint from the beginning when the trim is already in place.
Well put. Back in the day, us carpenters puttied and caulked paint grade, now it seems they leave it for the painters, lol
Sorry, I thought the OP was talking about pre-painted finished molding. I’ve seen that sold before.
Didn’t think about primed molding. I know that’s out there too.
Lowes sells both.
Primed
Painted
Well, being that is for door stops or windows you might be able to get away with that, but after it is installed you still need to fill in nail holes and caulk. No pro carpenter would ever install pre finished painted trim and walk away… it gets dinged going to the job, carried, being cut, etc. It always has to be touched up.
That would be nice though.
believe me, When you are running a thousand linear feet of baseboard in a house, it must be painted after it is installed. 
And if I leave an imperfect joint, and don’t fill it, chances are they won’t, even though they always say they are going to do it. I came back to a job the other week, no inside miters caulked they were nice and tight but still need to be dapped. WTF?.
And yes even if it is sprayed on site before installation it has to be painted once installed.
There are some fantastic acrylic gloss’s now that look really good brushed or rolled. The painters get these super fine pile rollers that do a fantastic job.
This thread reminds me of a great tip for DIYer’s installing baseboard. You have probably found that when you try to nail the base at a corner, the miter at the bottom tilts in and leaves a gap.
This is because the drywall is butted to the ceiling and leaves a half inch or so gap at the bottom. Drop a small block of half inch plywood behind the base on each side of the corner.
This acts as a shim or backing and keeps the base from tilting under the drywall.
Usually not a problem since drywall is installed before the hardwood floor, which takes up that gap. If no hardwood, then you gap the base off the subfloor anyway for the carpet.
Oh, and it’s moulding. Mold is what you don’t want in a house.
Or, if you don’t want to appear British, it’s millwork.