Not a good scenario
Integral colored concrete will absorb anything just like regular concrete.So bottom line is yes it is now stained,sounds like he has you over a barrel.I trust this is a lesson learned,always cover objects with plastic.
As for a fix?.I would be tempted to try liquid color from home depot/lowe's and dilute a small batch and try a "very" small spot with a small brush to if it will color in.Beyond that acid staining is your only other option,not fun but doable.You just need him to sign off on it.Remember you may have to stain the whole walk to get an even application.
You will probably need to seal it after done,no biggie.Just follow the directions.Also sealing needs to be done every year to protect concrete,this owner probably didn't.
Just some thoughts from a concrete contractor
· 1 decade ago