Try cooking oil. It works on many things and is gentle on your hands. Latex paint is a good example. I removed burnt pine sap from my hands with french fries – the oil in them did it.
I found this pretty awesome hand cleaner that has so far taken off everything I had ever gotten on my hands. It is called Tarkelp I last found it @ the Harbor frieght store but also found it at Big Lots. You can get it on line from a distibutor I bought 6 tubs of it.
Easy on the skin and no smell left behind. and it CLEANS really good.