Sizing new plastered walls and ceiling

[sjaisie]

I have recently had some plastering done to walls and ceiling. These will be wallpapered using blown vinyl and patterned paper.
Previously I have used a watered down wallpaper paste to seal the walls but this has always been hit and miss, and not sure if there is anything better to use.

Can I have your thoughts please?

 

[Wayners]

Bare plaster
I always painted to seal or sealed with Gardz.
Then use a ready mixed paste and applied will a roller. Ready mixed paste has less water in and sticks better.

I never sized with paste. Things have moved on.