I papered my living room (Graham and Brown paste the wall). On the chimney breast, the base emulsion was yellow on top half and white on bottom half. Unfortunatlely, I can in certain lights see the colour difference thru the paper !!. I am going to strip and paint the white with fresh yellow emulsion(the rest of the room had yellow). I have read that you have to remove all traces of paste prior to painting. The question (eventually) is ..... Is this cos the paint will discolour or cos it will flake off. I am not bothered if it discolours a shade as i am papering over but i am bothered if it will not be sound. Thanks