Prepare for painting with sugar soap or fine sandpaper?

[Ali Coaker]

I want to use white gloss to paint some white doors inside the house.

The doors were painted with white about 15 years old and are getting discoloured.

I know preparation is important but in this case I have to compromise!

I'll use white undercoat and one topcoat of gloss. The undercoat is to even out the surface and prevent discoloured patches showing through.

QUESTION: If I can use either sugar soap or fine sandpaper to prepare the surface (plus filler for holes) then is it better to use fine sandpaper than sugar soap?

[Stuart Noble]

Even a five minute rub down with fine sandpaper makes a big difference. Use as much undercoat as you need to hide the imperfections, then one thin coat of gloss

[Bovvered?]

I've always had good results using sugar soap and giving the paintwork a good scrub with the rough side of one of those pan scouring sponges. Then a final wipe over with white spirit. The only mistake I've made is thinking I could get away without the undercoat, looks great when done but starts yellowing in a matter of weeks

[whisky-dave]

I was also thinking along these lines having a similar job to do. So I've decided to try some of that wet 'n' dry sandpaper using a sanding block and a bucket of sugar soap solution in one go, seems to work OK but I also wiped down with some old rag immediately, this seems to help get rid of the dirt. It takes a while though, I don;t think it'll be safe using an electric sander with sugar soap. :)

[Andy Dingley]

That's a false dilemma. You use both, if you care.

If forced (especially anywhere near a kitchen), I'd go with the sugar soap alone. Unless you've already washed down and degreased the paint, sandpaper used alone will clog before it achieves much. I wouldn't even use sandpaper - this is definitely a job for an open mesh abrasive, such as wire wool or a plastic mesh Webrax/3M if it isn't too bad.