[Smokin' Joe]

Not sure how this would work on that particular rock and the concrete, but we use it to get oil based drilling fluid off of drill cuttings: Citrisolve

It works best of anything I have tried, and I have been examining rock samples from oil based drilling mud for well over 20 years.

As for the puke(s) who did this, I think this would be a fine time to bring back public flogging and the cat.

[shadowcat]

Thanks for the link.
I will check it out on some plasters I’m involved with.

Flogging and skinning is more my style.

[pillut48]

How do you feel about drawing and quartering?