Jerry wrote:
"Dave Osborne" wrote in message
...
: The parents have had a patio laid in Indian
sandstone/limestone. Dad
: decided to try getting a few mortar stains off with acid-based
patio
: cleaner. After a week or so, the patio has turned orangey-brown
where
: the acid has been.
:
: According to paving expert, the acid staining is permanent. :-(

He or she is probably correct...

:
: Anybody know if you can get rid of acid staining?
snip

Sand blasting, removing the stone to below the level of the acid
damage - a bit 'kill or curer' though...
sandstone is not damaged by acid.