I Totally agree with Roughcaster. That is the right way to do it!!!
I have done this sort of thing commercially and residentially for decades!!
A little naughty way with less work and less money.
stanlyknife the crack out about 10 mm at the right angle.
dust off as much as...
Hi Darren
The gyprock bonding is as good as they say i have done this before.
as long as the wallpaper is sound but remember it will get wet on application of the sealant and may come away.
I would give it 2 coats of sealant
coat 1 I would water down a little for your whole room...