Hi Richard,
Thanks for a detailed reply.
OK - the wall is original plaster. The house was built in 1898 and if I ever find any wall / surface / frame or anything else which is truly plumb & flat ...... I'll pass out with shock
Made tiling a nightmare. The walls around the bath were as straight & true as a politician
Work below where the PB is (services to toilet, basin, etc..) caused some of the plaster to begin a slight crack in plaster surface. To make the upper wall look better, I've used moisture resilient PB from 3' height to ceilling.
PB is fastened to wall mechanically ( M6x60 nail-in fixings ) sunk below level of PB then skimmed with joint filler.
Wall wasn't flat to begin with, and to be honest, a perfectly flat 'new' wall would look kinda out of place in our property
so all I'm looking to do is skim the wall to give a uniform finish.
The ceiling in the bedroom was D&D re-skimmed last year by pro's following storm damage to the roof (insurance claim) and I know is sounds daft but the billiard table smoothness of the ceiling compared to the old one looks out of place.
I have used true AquaPanel for all the wet area's or areas likely to become damp. When wet get this wall ready for painting, it'll be sealed again against dampness, just as an added extra to the moisture resilience of the PB, and all the paint we use will be suitable for the job in hand.