Cleaning stone / Removing stains

[dimuc]

Someone has splattered what looks like plaster/ paint onto my house wall which is an old stone rather than brick, i have tried paint remove spirits and it makes no difference, also tried sanding and again no difference other than making a mess of the stone, can anyone advise on perhaps chemical based materials? I have uploaded some pics that might help.

Thanks

 

[joe-90]

Pick it off bit by bit with a Stanley knife.

 

[dimuc]

tried that but its really stubborn, it would take me ages to pick away and it, pictures only show a few drops but there is quite a lot to shift.

anyone recommend brick acid perhaps?

 

[joe-90]

It looks like masonry paint. You won't shift that in a hurry.