Cleaning Concrete dried film on slate

[jb]

Our inground pool has slate tiles surrounding it and set in concrete. The concrete had cracked and chipped out. We mixed up new concrete patch and filled in the voids. We didn't do it neatly and now have concrete residue on the slate. It's mainly a film. Whats the best way to clean this up. It's been a week since we did the job. Thanks for your help

[Nate Nagel]

I'd try wiping it with vinegar, acid is usually the ticket for cleaning up concrete

nate

[HeyBub]

There's a product used to remove mortar skim from tile that may help. Check your local tile store for "Grout Haze Remover." Most contain Sulfamic acid.

Check:

and the nuclear-strength products:

[Sac Dave]

Muriatic acid is used to clean concrete ( more eating a layer off) , you might try a small spot, read up on it it will burn you bad. Not sure what the effect would be on slate.