How? I hate abscesses 
The first thing I’d try would be grease remover (sold at auto shops).
Brake cleaner. Also from auto parts store.
As it is derived from shale oil, try any of the many products sold for use on oil and grease on concrete garage floors. I think that the best to hope for is making the stain less evident, not complete removal.
You could also try Dawn dish soap.
1 Like
In my experience pretty much everything wears off eventually. Icthamol isn’t nearly as bad as Koppertox or Thrushbuster. Although my nephew spray painted some buckets with Alu Shield and that’s proving to be long lasting.
Runoff might get to a place where horses have to interact with it so I’m not inclined to use something ultra toxic, if I can avoid it. Thanks for all the suggestions.
There is some stuff called Krud Kutter that cleans just about everything. I heard about it from the guy who restored some antique furniture. He uses it for the initial cleanup. There are a number of different formulas. I found them at Home Depot. The basic one in the red spray bottle takes dried latex paint off anything. The painter tried it when he painted the bathroom and switched immediately. I’ve gotten sharpie off plastic. It comes in a gallon bottle concentrated so you can water it down depending on what you are cleaning.
Deleted - posted in wrong spot, sorry.
