QUESTION

How to Remove Cement Haze on Flagstone - Can you tell me if there is a product that will take "concrete haze" off of flagstone. When we grouted our flagstone with concrete we wiped off the excess concrete off the flagstone but it left a haze. Any ideas?

ANSWER

ANSWER - Generally speaking it is not recommended to use acid on stone or ceramic tile, although the only time it does make sense is when there is a cement haze on the stone. NEVER use anything like muriatic acid because it will do a lot of damage.

It is normally recommended to use sulfamic acid which is less corrosive and takes a bit more effort to use. The best thing to do is go to a cleaner manufacturer and use a pre-diluted cleaner for this purpose. On our website under resources and links there is a page with a list of manufacturers of cleaners and sealers with links to their website. While you are there select a sealer to seal your stone after it is perfectly clean and dry.

Sometimes you can just use vinegar diluted with water and it may be enough, but maybe not. It is best to purchase a pre-diluted acidic cleaner.

Before apply the acidic cleaner make sure the flag stone is saturated with water so the acid solution will not absorb deeply into the stone. Use a brush to scrub with the cleaner. Afterwards make sure you flush the area with clean water until the acid is gone. Good luck.