Just moved into a house and the previous owners were very heavy smokers, so the walls and ceilings are yellow from nicotin stains. We are repapering most of the house but were hoping to just repaint over wallpaper in the hallway/landing and ceiling. I believe we have to paint a stain block first or the nicotin will come through the new paint. What is the cheapest/effective way to do this. Stain block paint appears to be really expensive. I think someone years ago told me to use PVA glue but not sure if thats true or not. All suggestions gratefully received.