I used a 10:1 mix of DI Water & sulfuric acid. I accidentally spilled some and it cleaned everything off my tile and made my grout look brand new again. Not sure about SSKI though. I am sure Trapper will know.
Thanks. I don't have any sulferic acid on hand. What do you keep that around for?
I think they said hydrogen peroxide makes it worse... and it does. What a mess.
There was a good thread on it years ago.