Painting our hallway today – wondering how best to approach all the door frames that will be gloss white. As I understand it, you should lightly sand all the woodwork to give the new paint something to adhere to – do you need to go to town on this, or is a quick run-over with sandpaper sufficient?
I guess I also need some sort of filler to go over all of the paint chips (there are loads, doubt the frames have been painted in 20 years) – any recommendations for what to use? Thanks.

Best finish would be if you took all the paint off, but that’s a right ballache. Remember, whatever the base is like, it will always show through. Mine are in a right state, probably 60 years worth of different layers. Lots of chips. Tempted to rip out the frames and architraves in my house and replace with new as will probably be less effort!!

If the paint on there is really thick and rounding off internal corners etc you may want to strip it back – heat gun and scraper and a lot of time.

As for chips most people just sand them down a bit to taper the edge and then paint over them. Depends how perfect you want them to look. Personally I can’t be bothered unless I have a big dent in the wood and then use a filler, allow to dry sand and do a quick primer coat, allow that to dry and sand that back a bit before doing the whole lot.

If you are doing lots of woodwork consider switching to water based satinwood finish over gloss. Much easier to get a decent finish, no smell and won’t yellow.

Don’t take all the paint off. its not necessary as long as what’s there already is in good nick and not peeling or bubbling. I’d just sand it back with some medium sandpaper, wipe it down to get rid of any dust and sanding dust. Fill in any divots or blemishes and just give it one coat of undercoat then straight on with the gloss. I’ve always had decent results with this method. The biggest dilemma I usually have is do I peel back the carpet or mask off the carpet and paint down to the carpet? I’ve tried it both ways and still not sure of the best approach. Not even sure if the coat of undercoat is necessary but I do it anyway.

you are doing lots of woodwork consider switching to water based satinwood finish over gloss. Much easier to get a decent finish

Only bit I disagree with, IME oil based gives a much better finish than water based – it’s longer drying time means the brush marks fall out leaving a flatter finish. Water based easier to apply and won’t yellow though. IMO, of course

Water based gloss is rubbish. Solvent based is where it is at but then I’ve never formulated a water based paint only ever done solvent and solvent free stuff. Yellowing has very little to do with the water/solvent – it is the resin chosen – polysiloxanes are normally considered the best for gloss and colour retention but they don’t make it onto the consumer market.

A thorough sanding is better, particularly around any detail (if you have panels). You don’t need to go back to wood but it needs to be smooth – any defects will show up. The quality of your substrate will have a large impact on the quality of your finish – so it is worth doing well.

My personal preference would be for a solvent satinwood. The less glossy the finish, generally the better it hides any defects.

Water based paints are great but you do need to buy fine haired brushes designed for use with them to get a good finish.
( and buy decent paint)

Gloss is unfashionable and reflects, showing all the blemishes. Satin is much better and looks smarter.