Although wallpaper can be directly pasted to clean previously painted walls, to ensure the best outcome and longevity on your job we recommend using Porter's Wallpaper Size. The benefits of using a wallpaper size:
Size evens out the porosity of the substrate, which in turn, allows the wallpaper paste to dry uniformly.
Size makes wallpaper easier to hang by allowing a bit of slippage so wallpaper can be accurately slid into place.
Size enhances the holding power of the paste.
Size makes the wallpaper easier to remove.
For porous surfaces apply one coat of undiluted glue size with a brush or roller. Allow 2 hours dry time. For non-porous surfaces Porter's Wallpaper Size can be diluted by adding 1 part water to 2 parts glue size, apply with a brush or roller and allow 2 hours dry time.
Coverage: for every 1 roll of wallpaper, you will need 500mls of glue size (undiluted). When diluted 500ml covers enough area for 2 rolls of wallpaper.