We're preparing solid plaster walls for painting. One section was particulary bad and we've done alot to repair it. It now has undercoat applied and under room lighting looks good, however when the afternoon sun shines across it it looks like a bit of a moon scape.

Because this wall is so prominant we're thinking of hanging lining paper, then painting to match the rest of the room. The section is bordered by door architraves, the skirting and a picture rail, so blending in shouldn't be an issue.

However the lining paper instructions specify sanding back acrylic paint and then applying an oil-based sealer. Will pre-pasted lining paper not stick to acrylic undercoat?

Also, does anyone have experience with pre-pasted wallpaper? Mine isn't too good. Can you still apply paste, say to the wall, and then apply the soaked, pre-pasted paper? Any advice would be much appreciated.

I think you may be solving one problem and replacing it with another.
If you use lining paper and then painting, you may make the surface better but you will probably see the paper joins even after you paint it and the paper will tend to follow the bumps so they may still show up (you will be putting on an even paper coating which will put the same amount on the high spots as well as the low spots, it won't bridge hollows).

Water based acrylic undercoat can be pasted over, usually you coat it with a wallpaper size (if you use any vinyl paper the size should have a mould inhibitor ) but it wouldn't hurt to use this type anyway.

If the paste is poor (doesn't melt easily or appears to be reral thin) you need to use warm water and if you think its still a bit suss you can use a cellulose paste and paste the paper with a brush on the back instead of dipping the paper. Painting the wall with paste could be done but I think it would be safer to paste the back of the paper as if it was unpasted.

Any good wallpaper shop should be able to sell you the right gear for whatever product you have bought and check what they say (thats if you can find someone with the knowledge these days).

The wife was in the wallpaper business for years and we often pasted wallpaper which was prepasted when it looked a bit suspect.

I suspect doing other ways might also work but if you get it wrong it can be a nasty and expensive exersize. It would want to be a really bad wall, I think I might try to get the surface a bit better and use flat paint to minimise the reflection onto it.

Best of luck.

PS what about a lot of pictures on the wall !!!