How do I remove hardened grout residue from unglazed tile?
Grout remover is the only thing I know of that might work without ruining the tile. I’d only suggest that you try using a nylon scouring pads instead of a stiff brush. But other than trying a different brand of grout remover (I’m not familiar with Aldon directly), you’re doing pretty much the only thing you can do. Good luck!!
