When someone says "I've always thought an emulsioned wall gives a nice smooth, plain-coloured surface that's good to paper to later", then i ask myself what does this actually mean ! Cos when someone says 'emulsion' then the problem with it is there are soooooooooo many types of emulsions out there that all have different ingredients. This causes sooooooooo many contradictions when someone says 'emulsion', if u all see what i mean. However, "liamcaswell" if you coated all your walls with a thinned vinyl matt as a mist coat and then coated them with a silk, then you would have no problems with wallcovering over it. But because the silk has been directly applied on the new plaster then unfortunatly the silk is only sitting on the top of the new plaster surface (even when thinned). Also, cos you I asked the oldest guy in B&Q what paint you could use for the mist coat & He pointed you to Crown Brilliant Silk Emulsion, then this means nothing if the old guy was not an proffessional decorator. In other words, he is just an old guy with b&q clothing on. Though maybe he claims he is an decorator. If i were you "liamcaswell" & you insist in wallpapering one wall then i would give the one wall two coats of Dulux Trade Vinyl Silk and leave for 28 days (to fully cure), then line the one wall and leave 72 hours to dry, then apply your chioce of wallcovering. But i personaly would be more inclined to keep emulsioning all your walls for many years to come as this will cause no problems. Also, "JohnD" it is Soft Sheen, Silk,Acrylics & some matt's that can blister when they are used as an sealer on new/bare plaster.