I posted a problem I was haivng with a wall in my house that had been treated with a man made material, to help prevent dampness problems but it was to help cure condensation probelms.
This treatment when expsosed by the covering paint having flaked off ruined the wallpaper by brown stains appear over a period of time.
I was suggesterd i use an oil based paint or a alkoli sealer.
I suspected it was a tar based product, I had it covered with a oil under pait, bad move! it reacted with the covering and took ages to dry.
I then had it painted with an aluminium pait which is used to under coat wood and it claimed to seal bitumen, BINGO!
This has saved me the work of having to reline the wall.