Had carpenters at home and they spilled some foam around them which they removed but left ugly stains behind, both on granite steps and on concrete slabs.
Is there a good way to remove the residues without leaving ugly discolorations on the slabs?
Hardened foam is most easily removed mechanically. It's not that hard, so you can rub it off with almost anything. If you use solvents, you risk spreading the stain and making it more set in the surface.
