removing bitumen film from plaster

[helcat]

Hi there

could anyone tell me please how to remove some old bitumen film from my bedroom wall? The wallpaper was brown and discoloured (despite having lining paper) over where the film is and I would like to get it off the wall and use a paint on damp sealer over the plaster instead. However despite scraping and using coarse sandpaper The film is firmly stuck and I'm getting nothing more than bits off it. I don't know what sort of glue was used to stick it on.

Any ideas would be welcome!
Many thanks

 

[Zampa]

It could be bitumen backed lining paper its stuck on with a special glue to help prevet damp stains etc

Give it a soaking with white spirit..that might soften it..it a coat of the damp sealer then line it.

 

[helcat]

Thank you very much Zampa - I'll give the white spirit a try

Best wishes
Helcat