I paint a LOT of this type of wood. If you apply paint to it with no prep it will look awful.
It depends on what sort of finish you expect. If you want an immaculately smooth, pristine surface then you would
have to use many coats of primer to build up a surface that can be sanded back. Or even Gesso. 10+ coats is not unusual.
This amounts to a great deal of time and effort.
I use a less irksome system where I fill the grain using a generic fine surface filler which I apply with a wet brush in the
manner of shaving soap. As it dries I go over it with a J-Cloth to take the excess off and work it into the pores.
When dry I sand it down a bit with coarse sandpaper so there are no lumpy parts or 'nibs'.
Two coats of primer then go on. If you take your time filling the grain then the primer coats need minimal sanding, Just flatten any
brushmarks and dribbles with 80-120 grit paper. Flexible sanding pads are the thing.
Then you can apply the top colour coats. I use artist's acrylic, always brushed on. You can spray but frankly it's a lot of faff IMHO.
As I said, it depends on the finish you want. If I wanted a perfectly smooth surface I would tend to find a factory-finished moulding
where the prep has all been done for you and spray that. You need to establish that the paint you are spraying will 'stick' the the moulding
properly. I generally sand it back a bit and give it a 'key' coat of Shellac. Shellac is organic and porous. It will bond well to most things
and water-based paint will stick to it. *This isn't always the case so test a bit first.
To me, a painted surface that has a few textural 'imperfections' looks better than a dead flat one. That's my excuse anyway....
