Gypsum plaster on old wallpaper

[Notch]

I am going to apply plaster on the walls in a room, does it work to apply it on the wallpaper or do I need to remove the old wallpaper first?

The wallpaper has been up for about 1 year, with regular renovation plasterboard underneath it.

 

[jonaserik]

Gypsum contains vätai, wallpaper is paper and absorbs moisture/water and comes off, normally taking down wallpaper involves wetting it, so it's not good to plaster on wallpaper, it should be removed (PUH)

 

[Notch]

That's what I was afraid of...Thank you for the answer