Don't laugh, damp/ bitumastic problem.

[anobium]

I diagnosed a neighbours damp problem as being caused by an open wall floor joint and told him to make this good using a waterproofing sand and cement mixture.
Unbeknown to me he then decided it would be a good idea to cover the areas of damp plaster with a bitumastic waterproof solution.
After realising his mistake, (it will leech through his expensive wallpaper)
he his now faced with the problem how to get rid of hit.
My only suggestion is a solvent, ie petrol, has anybody any better ideas apart from removing the plaster?

 

[noseall]

Do not use petrol indoors!

white spirits readily dissolves bituminous products.

 

[anobium]

Do not use petrol indoors!

white spirits readily dissolves bituminous products.

Quite right noseall, god knows why I wrote that.

 

[joe-90]

It'll dissolve the tar but then it will leach into the wall and you'll never get rid of it. I doubt it will leach if the areas is dry. Or use a stain block.