What happens if I don't sand wood before painting?

[Grockle]

I sanded all the woodwork last year and painted it with white eggshell paint. Some of it is yellowing already (and I used Dulux paint) - maybe the creamy colour that it had been painted before?

Anyway, I need to go over some bits again - I prepped it all properly last time but do I need to do it again? Can I just wipe it with sugar soap and paint over it?

Sorry, you need to sand it again, roughly, so the new paint has something to "key" into.

There was a problem with some batches of Dulux white yellowing, can't recall why.

Nooooo! Not what I wanted to hear! Can I just do a quick rubdown? I didn't know that about Dulux paint. I'm very cross now!

It needs re-doing anyway - grubby marks at small-child-height

i never do, it stays on, though i am sick of yellowing gloss too!

Yes, a quick rub down with sandpaper is enough, you just want to rough up the surface a bit.

It was Dulux, but it was gloss paint.

Ok, will rough it up a bit if I can be bothered

Slight concern over the paint as it's been in the shed for 12 months - it'll be ok, won't it?

use quite a fine sandpaper, you only want to take the shine off and give a key for the new paint to stick. If you scratch or gouge the surface you wil have to undercoat and flat down.

The yellowing is a known problem with low VOC oil paints that came onto the market in the last couple of years. It is not specific to Dulux.

If you can expose the painted surfaces to sunlight - even by opening doors into the hall during the day - it will help the yellow to fade. Outdoor surfaces do not suffer as they are usually exposed to sunlight.

Water-based gloss is not IMO so hard wearing or shiny, but it does not have the yellowing problem.

Dulux have issued paint to a new, allegedly non-yellowing formula. In the Dulux Trade range, it is sold in tins with blue lids.

p.s.

If you use the same paint out of the shed, it will be the same as the paint you used before, so it will go yellow. Buy new.

Thats true, Piglet, I hadn't thought of that. I think the eggshell is a new tin - it's the emulsion that is old and that hasn't yellowed. Interestingly, the only door that has yellowed is the toilet under the stairs that pretty much never sees daylight. The other doors are fine. I wonderedn about using a primer to stop it seeping through again/

I'll have a good look round B&Q tomorrow! Thank you.

I don't think it's seepage, I think it's the type of oil that was used in the paint manufacture.

Tests of paints are often done by painting jointed wooden panels and exposing them to the weather to see how well they last without cracking or peeling; this kind of test would not spot that in sunless conditions they go yellow. I expect the tests have been changed following the yellowing problem.

Emulsion paint is water-based, and does not have the yellowing problem of low-VOC paints

Get in touch with Dulux. I got a load of vouchers after emailing them after watching WATCHDOG which had an article about the yellowing paint problem. Some people even got their painting done for them, paid for by Dulux. I used Dulux One Coat btw.

I hadn't thought of that frigid... maybe I'll contact them too. I've repainted today so hopefully that will sort it.

Thanks for all the help