Yes indeed, it is the only way.. Any already Glossed woodwork must be rubbed down sufficently to allow a decent enough key for a good undercoat. Only then can Gloss be applied as a finish coat. ( Gloss will not adehere to old Gloss )

Hope this helps..

This is how I would go about re-painting doors
1, Sand down
2, Dust off & wipe down with sugar soap
3, Undercoat x 1 coat leave to dry,
4, Light sand then Gloss

Give the doors a light ru down with fine sandpaper then apply a coat of undercoat and the following day a light rub down again then apply a coat of gloss and they will be as good as new

Hmm ,well if you want a good decorative finish then yes.You need to create a key but you need a vechicle for that key so abrade back and front,prime,undercoat and gloss. Your doors will look like new.
If you just paint them then in a month or so that coat will just peel off like cling film.
chris

It is very important to rub the gloss down to provide a key for the new paint system, preparation is the key to good decorating. as for your yellowing gloss, you could use a more eco friendly water based gloss or satin finish which will stay white much longer than traditional oil based gloss or satin as it is the oil in the paint which tends to turn yellow. One note though water based gloss is not as glossy as traditional oil based gloss.

Del the painter spot on! never never gloss on gloss, doesn't key

Yes you need to sand the doors to make sure you have exposed existing painted doors to abrasion. Then you use Dulux Brilliant White Undercoat(solvent based)to prime surface. If you normally paint your doors perhaps every year or every 2 years, Dulux brilliant white gloss is ideal. For a longer whiteness on doors then I will recommend you use Dulux (brilliant white) Eggshell for finishing.

Hello there,
First you have to fill any holes or cracks, then sanding down to make them smother, and then apply 2 coats of gloss. Hope this help,
Regards
Mike General Building

Hi there,
rather than sanding them down which is time consuming the easier way would be to use a paint stripper like nitromors. It will take the layers off a lot quicker, give them a light sand over and then prime, undercoat and re-gloss them.
Hope this helps.

chris

Preparation is key to a good finish with any paint product, but with gloss you'll get noticeably better results if you spend a little extra time preparing the surface. The simple step of rubbing down the undercoat with wet and dry paper, for example, helps the gloss to flow on better, giving a shiner finish to the job.

I would do your doors in this order:-

Fill any holes and blemishes
Sand down
Paint with 1 coat of Oil-based Undercoat
Check the door has no more holes/blemishes, if it has refill
Sand down agan with fine sandpaper
Paint with 1 or 2 coats of Oil-based Gloss or Eggshell

I would also do the same steps for doors/woodwork that need to be stained or varnished.

If the doors are yellowed that could mean they are coated with nicotine if there has been a heavy smoker living in the property. If so wash the doors down with sugar soap before sanding them with p120 sandpaper. Then apply an even undercoat with a decent brush or you can use a short haired or mohair mini roller and lay off with a brush. I would roll them if the doors are flat faced doors to save time and decrease the chances of any sags or runs when brushed on heavily. Finally apply a gloss. Good luck and happy painting. : )