Clean tar - Remove tar from setts

[Celia]

Is there any way of cleaning tar from setts? we have large numbers, some of which have thick tar on the surface. We can remove that but getting rid of the film of tat on the surface seems impossible. Some others have partial traces only, so there must be a way.
We believe the setts formed a road surface years ago, then they were tarmaced over. All suggestions welcome, please, (apart from giving up!!!!) Thanks

Celia

[lutonlagerlout]

I recall the gaffer saying that years ago blokes would work on cold nights doing this,not much fun but it come off cleaner in the cold
other than that some kind of solvent but would work out expensive
LLL